GRADE 10 SCI MODULE UNIT 2

i
10
Science
Department of Education
Republic of the Philippines
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Learner’s Material
Unit 2

ii
Science – Grade 10
Learner’s Material
First Edition 2015
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Unit 2: Force, Motion, and Energy
Overview
Module 1: Electricity and Magnetism
I. Introduction----------------------------------------------------------------------------------83
II. LearningCompetencies/Objectives---------------------------------------------------83
III. Pre-Assessment -------------------------------------------------------------------------84
IV. Reading Resources and Instructional Activities ----------------------------------87
Activity 1: For the Record -------------------------------------------------------87
Part A: Virtual Tour of a Radio Broadcasting Studio --------------88
Part B: My Own Home Recording Studio! For Life ----------------91
Activity 2: Test Mag….1, 2! (Testing for Evidence of Magnetism) -------93
Activity 3: Induced Magnetism ---------------------------------------------------95
Activity 4: Detecting and Creating Magnetism -------------------------------96
Part A: North meets south -----------------------------------------------97
Part B: By the touch of a Magnet ---------------------------------------97
Activity 5: Oh Magnets, Electromagnets ------------------------------------100
Part A: Watch their Domains! ------------------------------------------101
Part B: Within the Lines -------------------------------------------------103
Activity 6: Electric Field Simulation -------------------------------------------105
Activity 7: Magnetic Field Simulation -----------------------------------------107
TABLE OF CONTENTS
Activity 8: Magnetic Field Around Current – Carrying Conductors -------------110
Part A: Magnetic Field around a Straight Conductor ------------111
Part B: Magnetic Field around a Coil of Conductor --------------112
Activity 9: Making your own Electric Motor ----------------------------------115
Activity 10: Let’s Jump In --------------------------------------------------------117
Activity 11: Principles of Electromagnetic Induction ----------------------121
Part A: Inducing voltage and current in a coil-------------------------------122
Part B: Amount of Induced voltage and current vs number of turns----123
Part C: Amount of Induced voltage
and current vs. strength of magnetic field---------------------------123

Part D: Induced voltage and current vs rate of magnetic field change --124
Part E: Coil orientation and direction of magnetic field change --------124
V. Summary/Synthesis/Feedback -----------------------------------------------------131
VI.SummativeAssessment---------------------------------------------------------------134
Glossary of Terms------------------------------------------------------------------139
References and Links ------------------------------------------------------------141
Module 2: Electro Magnetic Spectrum
I. Introduction --------------------------------------------------------------------------------142
II. Learning Competencies/Objectives ------------------------------------------------143
III. Pre-Assessment ------------------------------------------------------------------------144
IV. Reading Resources and Instructional Activities --------------------------------144
Activity1:TheElectromagneticWaveTheory--------------------------------144
Activity 2: Now you go! Now you won’t ---------------------------------------149
Activity 3: Sound check ----------------------------------------------------------152
Activity 4: Then there was sound ----------------------------------------------153
Activity 5: It’s getting hotter -----------------------------------------------------157
Activity 6: Screen the UV out ---------------------------------------------------161
V. Summary/Synthesis/Feedback -----------------------------------------------------163
VI. Summative Assessment -------------------------------------------------------------165
Glossary of Terms -----------------------------------------------------------------166
Module 3: Light: Mirrors and Lenses
I. Introduction---------------------------------------------------------------------------------168
II. Learning Competencies/Objectives -----------------------------------------------169
III. Pre-assessment -----------------------------------------------------------------------169
IV. Reading Resources and Instructional Activities --------------------------------173
Activity 1: Mirror, mirror, on the wall ------------------------------------------173
Activity 2: Angle of Incidence vs. Angle of Reflection --------------------176
Activity 3: Mirror Left-Right Reversal-------------------------------------------177

Activity 4: Who wants to be a Millionaire?-----------------------------------178
Activity 5: Images Formed by Curved Mirrors -----------------------------182
Activity 6: Are you L-O-S-T after Reflection? -------------------------------187
Activity 7: YoU can be Magnified! ---------------------------------------------195
Activity 8: Are you L-O-S-T after Refraction? ------------------------------200
Activity 9: Making Improvised Optical Device ------------------------------209
Problem Solving Sheet ----------------------------------------------------------212
V. Summary/Synthesis/Feedback-------------------------------------------------------213
VI. Summative Assessment -------------------------------------------------------------215
Glossary of Terms -----------------------------------------------------------------219
Appendix A --------------------------------------------------------------------------222

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UNIT 2
Force, Motion, and Energy
(The electric and magnetic phenomena around us)

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UNIT 2: FORCE, MOTION, AND ENERGY
(The electric and magnetic phenomena around us)
Overview
The moving iron core within the Earth acts like a giant bar magnet. It
produces a weak geomagnetic field that surrounds and partially protects us from
solar radiations. In like manner, the moving charges within the Sun generate
an eruption of radiations. This produces a solar magnetic field that spreads
throughout the solar system and beyond. Moreover, a solar wind of charged
particles constantly interacts with the Earth’s changing geomagnetic field.
In Grade 8 Science, you learned some characteristics of heat, visible
light, and electricity whereas in Grade 9 Science, you were introduced to
the forms and sources of energy. You also learned how electrical energy is
generated, transmitted, and distributed. Using the principles of forces, motion
and energy, Unit 2 of Grade 10 Science which is intended for the second
quarter, supports investigations on the electric, magnetic and electromagnetic
phenomena all around us. Eventually, this unit will help you to understand the
different electromagnetic waves commonly known as the EM spectrum with a
final emphasis on the visible light.
In Module 1, you will be reacquainted with basic magnetism and its
relationship with electricity by exploring electric and magnetic fields surrounding
devices made up of magnets and current-carrying conductors.
Moreover, a detailed study of the characteristics of the EM spectrum in
Module 2 will help you appreciate the relevant applications and effects of some
of the EM waves to us and our environment.
Lastly in Module 3, you will study the nature of light as it interacts with
matter through reflection and refraction. There will be interesting activities on
image formations using different mirrors and lenses.
The chief goal of the activities in these modules is to acquaint you
with the particular phenomenon in study, enable you to observe relationships
between variables, help you to develop and communicate your tentative
explanations of the phenomena or models, and lead you to further inquiry and
deeper understanding.

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ELECTRICITY AND
MAGNETISM
I. Introduction
In this module, you will map two invisible force fields - the electric and
the magnetic fields. Within each field, forces may be exerted on matter causing
it to interact with another matter because of electricity and magnetism working
as two aspects of a single electromagnetic force.
You will further explore, demonstrate and explain the idea that a changing
electric field produces magnetism, and a changing magnetic field produces
electric current in the light of technological applications that are helpful to man.
At the end of this module, you are expected to answer the following key
questions below and use the learning competencies as study guide:
II. Learning Competencies/Objectives
1. Make a simple device that shows how a magnetic field exerts a force
on a wire.
2. Demonstrate the generation of electricity by movement of a magnet
through a coil.
3. Explain the operation of a simple electric motor and generator.
How is electricity related to magnetism?
How does electricity produce magnetism? How does magnetism
produce electricity?
How does an electric motor work? How does an electric generator
work?
What is electromagnetic induction?
Unit 2
MODULE
1

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III. Pre-Assessment
Direction: Choose the letter of the correct answer.
1. In which case or cases is electric field present?
I. A spark jumping between two nearby rods.
II. A charge that is momentarily at rest.
III. A rotating bar magnet.
a. I only
b. I and II only
c. II and III only
d. I, II and III
2. In which case can a magnetic field be produced?
a. A charged comb.
b. A falling glass rod.
c. A welder’s arc flash.
d. A rolling plastic cylinder.
3. Which device can be used to determine the polarity of an unmarked magnet?
a. a charged glass stirring rod
b. a gold-leaf electroscope
c. a sprinkle of iron filings
d. an improvised compass
4. How will you describe the magnetic field around a straight current-carrying
wire?
a. The magnetic field is strongest near and around the wire.
b. The magnetic field consists of straight lines parallel to the wire.
c. The magnetic field does not vary with the distance from the wire.
d. The magnetic field gets stronger with increasing distance from the wire.
5. Which statement about an electromagnet is TRUE?
a. The electric field surrounding a battery-powered electromagnet
alternates constantly.
b. The current in the electromagnet coil temporarily magnetizes the iron
core.
c. The electric field strength is inversely proportional to the current.
d. The magnetic field lines produced are all straight.

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6. What can be inferred from the alignment of compass needles in the set-up
below?
a. A permanent magnet is nearby.
b. The power switch was turned off for long.
c. The current-carrying coil becomes magnetic.
d. There is a constant and uniform magnetic field around the coil.
7. As part of a traffic light system, large loops of wire are buried beneath road
intersections. Which of the statements is NOT TRUE about the operation
of this traffic light system?
a. Vehicles driven over the buried coils activate a traffic light sensor.
b. The conducting loops activate a color–dependent field.
c. The alternating current sent through the buried coils produce an
electromagnetic field in each coil.
d. A minimum number of vehicles over the coils can trigger the traffic light
to change green.
8. Complete the following statement: Moving a metallic detector past a 5 peso
coin creates a secondary magnetic field that is most similar to that of __.
a. a horse shoe magnet
b. a flat refrigerator magnet
c. a current-carrying, circular loop
d. a V-shaped straight wire that carries a current
9. During the Student Technologists and Entrepreneurs of the Philippines
(STEP) Competition in Landscaping, a water pond transformer changes 216
V across the primary to 12 V across the secondary. If the secondary coil has
10 turns, how many turns does the primary coil have?
a. 10 turns
b. 18 turns
c. 180 turns
d. 228 turns

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10. What basic principle enables ALL electric motors to operate?
a. Iron is the only element that is magnetic.
b. Opposite electric charges attract and like charges repel.
c. A moving conductor within a magnetic field will experience an
electromotive force.
d. Acurrent-carryingconductorplacedwithinamagneticfieldwillexperience
a magnetic force.
11. A magnet moves inside a coil. Consider the following factors:
I. strength of the magnet
II. number of turns in the coil
III. speed at which the magnet moves
Which can affect the electromotive force (emf) induced in the coil?
a. I only
b. II only
c. III only
d. All three factors
12. Which statement about transformers is FALSE?
a. A step-down voltage transformer steps up the current.
b. Transformers use mutual induction.
c. Transformers are an application of Faraday’s and Lenz’s Laws.
d. A transformer can function with either an alternating current (AC) or a
steady direct current (DC).
13. What is TRUE about the intercom system that is shown below?
a. The part A of the intercom system serves as a microphone only, while
part C serves as a loudspeaker only.
b. Either parts A and C of the intercom when switched as such can be
used as a microphone or as a loudspeaker.
c. The microphone part only basically consists of wires, a cone
diaphragm, a magnet, and a coil.
d. The loudspeaker part only basically consists of wires, a cone
diaphragm, a magnet, and a coil.

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14. What transformation can take place in an improvised generator?
a. mechanical energy into electrical energy
b. electrical energy into mechanical energy
c. alternating current into direct current
d. direct current into alternating current
15. A loop of conductor lies flat on a horizontal table. A toy magnet is hanging
still over it with the magnet’s north-seeking pole pointing down. What
happens next?
a. The magnet produces a clockwise current in the coil.
b. The magnet does not produce any current in the coil.
c. The magnet produces an upward electromagnetic current.
d. The magnet produces a counterclockwise current in the coil.
IV. Reading Resources and Instructional Activities
GETTING HOOKED ON ELECTRICITY AND
MAGNETISM APPLICATIONS
AVPs: Veni, vidi, vici.
(Audio-Visual Productions: I came, I saw, I conquered.)
People readily adopt emerging technologies. The use of audiovisual (AV)
works be it in film productions, in business displays, or perhaps in education
innovations became a trend and it is here to stay. Examples abound like our
growing love for the high quality audiovisual components we listen to and
watch or the endeavor of school stakeholders to provide projection technology
in every classroom.
The rise of it all AV production, recording, and storing technology and
industries were made possible because of the discovery of the link between
electricity and magnetism. How does one begin to understand this partnership?
For a start, consider doing the activity regarding audio recording devices.
Activity 1
For the Record…
(Adapted from the EMI Teaching Sequence by Jenaro Guisasola and Kristina Zuza)
Objectives:
• Identify the basic recording equipment of a digital radio studio.
• Classify whether devices use electricity and/or magnetism when
used in recording audio.
• Start a literature search on electromagnetic induction’s role in
recording technology.

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Materials:
• pictures of the radio studio control and audio room OR
• video clip on a radio station tour, video player, screen, and accessories
• pen and activity sheet/science notebook
Procedure:
PART A. Virtual Tour of a Radio Broadcasting Studio
1. Read the scenario and study the video clip or pictures selected by your
teacher, similar to what is shown in Figures 1 to 3.
Figure 1. A control room of a local radio broadcast studio commonly known as the announcer’s
booth. (Used with permission from the RPN-DXKO Radio and Television Broadcast Station in
Cagayan de Oro City.)
2. On your science activity notebook, make a table, similar to Table 1. List all
the equipment that you can identify in the photo shown in Figure 1. Indicate
with a check mark whether the equipment/device needs electricity and/or
magnetism to operate.
Activity Scenario: During non-class hours, you frequently meet your friends
playing and making music together. One afternoon you decided to go to your
local radio station to ask what equipment and software is needed to start
recording at home.
At the broadcast studio, with the radio technician out, the staff allowed you
to take pictures inside the control room and live audio room, similar to what
is shown in Figures 1 to 3.

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Table 1. Radio Broadcast Studio Equipment (Control Room/Announcer’s Booth)
Equipment/Device Needs Electricity Needs Magnetism
Guide Questions:
Q1. How many of the devices you identified inside the control room
need electricity to operate?
Q2. How many of the devices you identified inside the control room
need magnetism to operate?
3. On your science activity notebook, make another table similar to Table 2.
List also all the equipment that you can identify in the pictures shown in
Figures 2 and 3. Indicate with a check mark whether the equipment/device
needs electricity and/or magnetism to operate.
Figure 2. A live audio room, commonly known as the newsroom, which is usually separated
from the control room via glass partitions.

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Figure 3. Back portion of a local newsroom
Table 2. Radio Broadcast Studio Equipment (Live Audio Room/Newsroom)
Equipment/Device Needs Electricity Needs Magnetism
Guide Questions:
Q3. How many of the devices you identified inside the live audio room
need electricity to operate?
Q4. How many of the devices you identified inside the live audio room
need magnetism to operate?
Q5. What other devices not shown in the photo may be used inside the
live audio room?
More Reading Support on Recording Technology:
What devices did recording technicians use in the past to record sound?
KEY CONCEPTS
• A typical broadcast studio consists of an audio console, microphones,
computers, studio monitors, and disc players.
• The audio console converts analog audio (voice via microphone) and
phone calls to a digital output. It also allows for the mixing of all sound
sources from CDs, computers, and other digital sources before being
sent to the transmitter. Aslider controls the volume of each sound source.
• The live audio and control rooms are connected by cables for the
exchange of audio and digital data signal during recording, mixing, and
even editing of all audio-video elements digitally stored on hard drives.

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PART B. My Own Home Recording Studio! For Life…
1. You could be an aspiring singer, a music artist, a student who needs to
record audio presentations or simply one planning to have a start-up home
recording studio. Use Table 3 and extend your understanding of the recording
industry by matching the devices in Column B and their respective functions
in Column C with the items in Column A. Write the letter and number for
coding your answer.
Table 3. A Home Recording Studio Start-Up Equipment
A
Coded
Answer
B C
Picture
Device
Name
Function
1. 1 ___ ___ A.headphone
I. Used for playing some
digital instruments, recording,
adding effects, and mixing
different sources of sound
signals
2. 2 ___ ___
B. studio
monitor
II. Microphones and musical
instruments are plugged into
this, which in turn is connected
to the computer
3. 3 ___ ___
C. audio
interface
III. Processor should be
reasonably fast enough to
record, edit, mix, store, and
master a copy of the record.
4.
4 ___ ___
D. digital
audio
software
(DAW)
IV. Converts sound into
electrical signal
5. 5 ___ ___
E. computer
unit
V. Used for “referencing” or for
checking what the mix would
sound like on the equipment
6.
6 ___ ___ F. condenser
or dynamic
microphone
VI. Used for connecting
audio interface, microphones,
studio monitors, and different
instruments
7.
7 ___ ___
G. cables
VII. Commonly known as
speakers but these give a
sound close enough to the
real sound input

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Extension Activity: Learn more about the basic audio-video recording devices
and make a graphic organizer on your science notebook. What parts inside
these devices use electricity and magnetism to function as such?
Guide Question:
Q6. Which devices on Table 3 are powered, entirely or partially, by
electromagnetic induction (the phenomenon of a changing magnetic
or electric field’s effect on electricity or magnetism)?
More Reading Support on Recording Technology:
In the development of the recording and data storage technology, what
questions might engineers ask?
Think of some questions by now about recording technology. Can handy
mobile phones or digital cameras serve as audio-visual recorder and producer?
How do these devices apply electromagnetic induction?

To understand electromagnetic induction and its applications especially
on electric motors and generators, the next set of activities will help you revisit
concepts about magnets and forces associated with it, checking polarities, and
analyzing magnetic fields.
KEY CONCEPTS
• Many of the recording technology are founded entirely or partially
on the relationship between electricity and magnetism known as
electromagnetic induction.
• Devices that detect and convert audio inputs to electric outputs
or vice versa are called transducers. Most transducers like
microphones and speakers use the “generator effect” characterized
by the production of forces due to a changing electric signal
within a magnetic field or a changing field near a current-carrying
conductor.

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SOME BASIC PRINCIPLES OF MAGNETISM
Activity 2
Test Mag...1, 2!
Testing for Evidence of Magnetism
Objectives:
• Identify the forces (attraction/repulsion) between:
a. two magets, and
b. a magnet and magnetic/nonmagnetic materials.
• Distinguish a magnet (permanent or temporary) from a non - magnetic
object.
Materials:
• pair of 3”- 6” bar magnets
• 6-10 objects made of different materials from inside the room
• science notebook and pen
Safety Precautions:
• Handle magnets with care so as not to drop those. These might
break, chip off, and weaken upon impact.
• Keep magnets away from computer units/screens, memory storage
drives and disks, magnetic tapes, mechanical watches, and the like.
Procedure:
1. Use a bar magnet and explore the possible effect/s it can have on the other
magnet when made to interact. On your science notebook, make a table
similar to Table 4 and record the observed force effect/s. Answer also the
guide questions.
Table 4. Interaction between two permanent bar magnets
What I did to the pair of magnets to cause
interaction…
Observed effect/s
(attracted or repeled)
2. This time, use only one bar magnet and explore its possible effect/s on six
to ten different objects found inside the classroom. Record the observed
effect/s on a table similar to Table 5. (Exclude record on objects with no
observed interaction with the magnet.)

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Table 5. Interaction of a bar magnet with other objects
Objects that interacted with the magnet…
Observed effect/s
(attracted or repeled)
Guide Questions:
Q7. What conditions with observable effects make magnets interact
with another magnet?
Q8. In general, what conditions with observable effects make magnets
interact with non-magnet materials?
Q9. What type/s of force can a magnet exert on another magnet?
Q10. What type/s of force can a magnet exert on non-magnet objects?
Q11. How will you distinguish magnets from non-magnetized magnetic
materials?
Extension Question: What are the magnetic materials found in the audio and
video recording tapes?
KEY CONCEPTS
• Magnets exert either a force of repulsion or attraction.
• If a force of attraction only is possible between an object and a
magnet, then the object interacting with the magnet contains a
ferromagnetic substance and is considered naturally magnetic.
• If a force of repulsion is also possible between an object and a
magnet, then the object interacting with the magnet may also be
a permanent magnet or a temporarily magnetized ferromagnetic
material.

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Activity 3
Induced Magnetism
Objectives:
• Induce magnetism in a magnetic material.
• Infer the polarity of the magnetized object.
Materials:
• bar magnet
• four 1-inch iron nails, screws, or paper clips
Safety Precaution:
• Handle the magnet with care so as not to drop it. It could break, chip off
and weaken upon impact.
Procedure:
1. Use the bar magnet and nails to find answers to the questions below.
Record your answers on your science notebook. Use diagrams to support
your answers.
Guide Questions:
Q12. What happens if you bring two iron nails close to (or touching)
each other?
Q13. If you bring a bar magnet close to (or touching) the first iron nail,
can the first iron nail attract and lift a second nail? A third one?
Q14. What happens if vary/change the distance between the magnet
and the nail/s?
Q15. If the north pole of the bar magnet suspends the first nail by attraction,
what is then the nails’s polarity of induced magnetism in the indicated
regions? Why?
Figure 4. Magnetic Induction on Hanging Screws
2. Choose the correct term from the enclosed choices that should go into the
blank spaces on the “Sum it Up Challenge!”

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Sum it Up Challenge!
A quicker way to know the polarity of a permanent or induced magnet
is by the use of a magnetic compass which you will be using in the next set of
activities.
Activity 4
Detecting and Creating Magnetism
Objectives:
• Identify the polarities and strengths of a bar magnet and magnetized
objects using a compass.
• Demonstrate magnetization by stroking.
Materials:
• at least 2 small magnetic
compasses
• one 3-inch iron nail
• masking tape or cork
stopper
• paper or any small
scooping device
• cellular phone/any gadget
with camera
• strong bar magnet
• narrow test tube (5/8” wide)
or clear straw (5/8” wide)
• iron filings
Figure 5. Materials for Detecting and Creating Magnetism

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Safety Precautions:
• Use the magnet, compass, test tube, and the gadget with camera
with care so as not to drop any of these.
• Make sure that iron filings remain sealed inside the test tube or the
transparent straw (cool pearl taped on both ends). Avoid the iron
filings from sticking directly to the magnet.
Procedure:
PART A. North meets south
1. Checking Polarity. Place one magnetic compass on a horizontal surface.
Then, move a bar magnet around and above it exploring the strength and
polarities of the magnet. If a cellular phone or any gadget with built in camera
is available, take pictures of the magnetic compass needle orientations
for different locations around the bar magnet. Draw the compass needle
directions and write your observations regarding the magnetic field strength
on your science notebook and answer the guide questions.
Guide Questions:
Q16. What happens when you randomly move the bar magnet
roundabout and above the compass one foot or farther? Nearer
than a foot?
Q17. Compass needles are tiny magnets that are free to indicate the
north and south poles of a magnet? What do you need to do to
know the magnet’s polarities?
Q18. What does the compass needles indicate about the iron nail shown
below in Figure 6?
Figure 6. Use of Compass Needles for Checking the Magnetism
PART B. By the touch of a magnet
1. Magnetization by stroking. Pour iron filings on a sheet of paper and check
whether the filings are still non-magnetized. If magnetized, stir or move the
iron filings gently on the paper.
2. Fill carefully the narrow test tube up to a quarter with these iron filings.
Cover with masking tape or cork.

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3. Hold the closed test tube horizontally. Shake or roll gently with your fingers
to level out the iron filings inside.
Figure 7a. Leveling the Iron Filings inside the Test Tube
4. Then when levelled, touch with the north-pole end of the permanent magnet
the test tube’s curved end. Move the magnet along the test tube from this
end to the covered end. Lift the magnet off the test tube and repeat with
ten or more strokes. On your science notebook, observe and record what
happens inside the tube.
5. Gently lay the test tube on a table and bring compasses near both ends of the
test tube as shown in Figure 7.b below. Observe and record what happens.
Figure 7b. Testing Induced Magnetism on the Iron Filings
6. Carefully shake the test tube as shown in Figure 7.c, without moving the
compasses. Test for the presence of magnetism again. Record your
observations.
Figure 7c. Shaking the Iron Filings inside the Test Tube
Guide Questions:
Q19. In step no. 4 are the iron filings in the test tube magnetized? If
yes, which end is the north and which is the south? If no, what
else can be done to magnetize it? Try and record your idea.
Q20. What happened to the iron filings magnetism after several shakes?

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Extension Activity: Can you magnetize also an iron nail by stroking? Do a quick
activity to know the answer for yourself.
Extension Question: What will happen to a magnet if it is dropped too often?
ELECTRIC AND MAGNETIC FIELDS
A Look Back in History:
In 1819, Hans Christian Oersted (ˈƏr-stəd), a professor in the University
of Copenhagen, discovered during a class demonstration that a current carrying
wire caused a nearby magnetized compass needle to deflect. This observation
fired up tremendous research on electromagnetism. As a result, the effect
on the motion of conductors placed within a magnetic field (such as in the
operation of electric motors) was also experimented much and paved the way
for practical electricity.
Twelve years after this discovery, Michael Faraday (ˈFer-ə-dā) conducted
his famous induction ring experiment showing that current can be produced
by sources of changing magnetic fields. This is the key principle to practical
generation of electricity.
The next activities should help you demonstrate and explain the operation
of electric motors and electric generators that basically work because of the
existing relationship between magnetism and electricity.
KEY CONCEPTS
• Materials which are attracted by a magnet are known as magnetic
materials. Iron, cobalt, nickel and many alloys of these metals like
steel and alnico are magnetic.
• Magnetic materials can be used to make permanent or temporary
magnets unlike the non-magnetic materials which cannot.
• Stroking is one way of magnetization.

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Activity 5
Oh Magnets, Electromagnet…
May the forces be in your field!
Objectives:
• Explore the magnetic domains of a latch magnet.
• Observe and draw magnetic field patterns surrounding different
magnets and magnet combinations.
• Observe and draw magnetic field patterns surrounding a simple
electromagnet and a current carrying coil of wire.
Materials:
• an improvised magnetic
board
• white bond paper
• a pair of latch/refrigerator
magnets
• small magnetic compasses
• a pair of bar magnets • one 3-inch iron nail
• 1 neodymium magnet • science notebook and pen
• 1 U-shaped magnet • 2-m copper wire (AWG # 22)
• 1 disk magnet • connectors with alligator clips
• 1 knife switch • battery holders with 2 AA
battery
(Flat plastic bottle, water/Glycerin, iron filings/iron sand or Bargaja)
Figure 8. Commercial latch magnets (commonly known as flexible sheet refrigerator magnets),
and an improvised magnetic board which is made by filling completely a leak-free, flat container
(preferably plastic) with water/mineral oil, and magnetic sand.
Safety Precautions:
• Use the magnets, compasses, and magnetic boards with care so as
not to drop any of these.
• The neodymium magnet is many times stronger than the ordinary
disk magnet that can hold papers on refrigerator doors. Be careful
not to get your fingers pinched between this kind of magnet and other
magnetic material.

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• Open after use the switch for the current-carrying conductors,
electromagnetic nail and the current-carrying coil.
Procedure:
PART A. Watch their domains!
1. Use an improvised magnetic board and a pair of latch or refrigerator magnets
similar to those shown below to observe magnetic field lines.

Figure 9. Sample latch magnets, commonly known as refrigerator magnets, and a magnetic
board from the public science equipment package. Together, when used, will make the magnetic
field surrounding the latch magnets visible. The iron filings suspended in the liquid inside the
magnetic board align along the magnetic field lines.
2. Lay each latch magnet under the magnetic board. Tap gently the board
until a clear pattern is formed by the iron filings. On your science notebook,
draw the pattern made by the iron filings on a table, similar to Table 7. Note
the orientations of the magnetic field pattern for each latch magnet. Label
if needed.
3. Place one magnet on top of the other. Make sure that they are arranged
perpendicularly with each other. Hold the magnet on top as shown in Table 6
below (first row). Slowly and gently pull the magnet (towards you) as shown.
4. Observe what happens. Record your observations on a table similar to
Table 6.

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Table 6 Interaction of a pair of latch magnets when dragged at different orientations
START OF THE
TILTED PULL
END OF THE TILTED
PULL
OBSERVATIONS
A.
Lightly drag the top latch magnet perpendicularly
across the other as shown below. Use the sides
with no sticker.
For perpendicular
orientation:
B.
Lightly drag the top latch magnet, in parallel, over
the other as shown. Use the sides with no sticker.
For parallel orientation:
C.
Lightly drag the top latch magnet obliquely over
the other, and at an angle to the horizontal. The
‘no sticker’ sides should face each other.
For oblique orientation:

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Guide Questions:
Q21. What have you noticed when you pulled the magnet on top
perpendicularly across the other? What does this tell you about the
magnetic field around the latch magnet?
Q22. How do you relate the flapping interactions of the latch magnets, at
different orientations, to their magnetic domains?
Ideas for Research: The hidden structure of a refrigerator magnet can serve
as a model for how a scanning probe microscope (SPM) works. This tool has
a super sharp tip that is only one atom thick, allowing nanoscientists to probe
across a nanoscale surface. (A nanometer is a billionth of a meter.) What new
recording materials did scientists probe, study, manipulate, and control using
nanotechnology?
PART B. Within the lines…
1. Place the different magnets and electromagnets under the improvised
magnetic board one at a time. Each time, gently tap the magnetic board
until a clear pattern is formed. On your science notebook, draw the pattern
made by the iron filings on a table similar to Table 7.
Table 7. Magnets and Current-carrying Conductors
Latch Magnets U-shaped Magnet
Between North – North Poles of Two
Bar Magnets
Between South – South Poles of
Two Bar Magnets

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Between North – South Poles of
Two Bar Magnets
Single Bar Magnet
Disk Magnet and a Neodymium
Magnet
Iron nail wrapped with current-
carrying wire
- +
Straight Current-carrying Wire
- +
Current-carrying Coil
- +
Guide Questions:
Q23. Compare the magnetic field patterns drawn in Table 7. What similarities
differences have you seen among them?
Q24. What do the magnetic field patterns, shown on the magnetic board
indicate about the strength of the magnets?
Q25. What do the magnetic field patterns indicate about the forces of
interaction between magnets?
Q26. How will you use the button compasses to describe/determine the
forces of interaction between magnetic poles?

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In the previous activities, you have detected and describe the invisible
magnetic field line patterns around different sources of magnetism using the
magnetic board.
Activity 6
Electric Field Simulation
Electric Fields, Forces, and Forms (E-3Fs)
Objectives:
• Predict the electric field directions and patterns in different locations
surrounding charges and combinations of it.
• Relate electric field strength E to distance quantitatively and
qualitatively
Materials:
• Table 8 Electric Fields, Forces, and Forms (E-3Fs)
• Science notebook and pen
• PC unit and accessories installed with PhET Interactive Simulation
(for an actual offline or online activity)
Procedure:
1. Study the letter-coded images of charges and electric fields in Table 8.
Each image will help you explore the PhET-generated electric field patterns,
electric field directions, and electric field strengths.
2. Match these images to the numbered descriptions shown on the upper left
of Table 8. Using the number and letter codes, write your answers on your
science notebook.

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Table 8. Electric Fields, Forces, and Forms (E-3Fs)
Electric Charges and Field Descriptions
Match the electric charges
and field descriptions with the
images shown below from the
PhET simulations on Electric
Charges and Fields. Write
your answers using the
number and letter codes on
your science notebook.
A
B
C D E
F G H

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Optional Activity: PhET-based interactive simulation on electric fields
• For online simulation, navigate http://phet.colorado.edu through a web
browser. Offline versions can also be downloaded and installed. Once
installed, simple click the PhET icon to open the installed program.
• Next click “play with Sims,” then “Physics,” then “Electricity, Magnets
and Circuits.” Then choose the “Charges and Fields” simulation. Click
“Run now” to start the simulation.
• Once the simulation opens, play with the controls of the simulation to
navigate.
The University of Colorado shares for public use an online and offline
version of “The PhET Interactive Simulations Project” under the Creative
Commons-Attribution 3.0 license and the Creative Commons GNU General
Public License at http://phet.colorado.edu.
Activity 7
Magnetic Field Simulation
Magnetic Fields, Forces, and Forms (M-3Fs)
Objectives:
• Predict the magnetic field directions and patterns in different locations
around the earth, a bar magnet and combinations of magnets.
• Relate magnetic field strength to distance quantitatively and
qualitatively.
Materials:
• Table 9 Magnetic Fields, Forces and Forms (M-3Fs)
• Science notebook and pen
• PC unit and accessories installed with Physlet Physics and PhET
Interactive Simulation (for an actual offline or online activity)
Procedure:
1. Study the number-coded images of magnets, compasses and magnetic
fields in Table 9. Each image will help you explore the *Physlet Physics and
PhET-generated magnetic field patterns, magnetic field lines directions,
and magnetic field strengths.
2. Match these images to the letter-coded descriptions shown on the upper left
of Table 9. Using the number and letter codes, write your answers on your
science notebook.

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Table 9. Magnetic Fields, Forces, and Forms
Magnets and Magnetic Field Descriptions
Match the magnets and
magnetic field descriptions
with the images shown below
from the PhET: Magnets and
Compass, and the *Physlet
Physics simulations. Write
your answers using the
number and letter codes on
your science notebook.
1*
2
3 4 5
6 * 7 * 8

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Optional Activity: PhET-based interactive simulation on magnetic fields
• For online simulation, navigate http://phet.colorado.edu through a web
browser. For offline version, click the PhET icon to open the installed
program.
• Next click “play with Sims,” then “Physics,” then “Electricity, Magnets
and Circuits.” Then choose the “Magnets and Compass” simulation.
Click “Run now” to start the simulation.
• Once the simulation opens, play with the controls to get used to the
simulation. You can move the compass and the bar magnet around
on the playing field and then add the earth. How does the magnetic
field lines change inside and outside of the magnet as you vary the
magnet’s strength? You can also use the field meter to qualitatively and
quantitatively compare magnetic field changes.
Sum it Up Challenge!
On your science notebook, make any graphic organizer that will compare and contrast
the concepts you learned about:
• The electric field and magnetic field patterns (directions and strengths).
• The electric and magnetic forces acting within the electric and magnetic fields.
The purpose of the next set of activities is to introduce current into a wire
conductor and observe the response of the compass needle at some locations
around the wire.

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Activity 8
Magnetic Field Around
Current-carrying Conductors
(Adapted from the DepEd-NSTIC Activity on Magnetic Fields and Electric Currents)
Objectives:
• Using a compass, explore the magnetic field around current-carrying
conductors.
• Use the compass to determine the direction of the magnetic field
relative to the direction of current through:
a) a straight current-carrying conductor; and
b) a current-carrying coil.
Materials:
• 3 wooden blocks with holes • 1 button magnetic compass
• 14 gauge insulated copper
wire, 20-50 cm
• 3 or 4 connecting wires
• 4 AA dry cell holders (in
series)
• 1 fuse holder with fuse
• science notebook and pen • 1 knife switch
• 5 cm2
used rubber mat • cutter
• 1.5 meter hook wire (#22,
stranded)
• tape
• 3-cm or 4-cm diameter
magnetic compass
Safety Precautions:
• Open the switch after observation to conserve energy. Batteries
and wires may become hot if current flows for very long.

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Experiment Setup A:
Procedure:
PART A. Magnetic Field around a Straight Conductor
1. Construct the circuit in Setup A as shown above. Make sure the switch is
open at the start. The wire should pass vertically at least 10 cm below the
wooden block.
2. On the wooden block, position the magnetic compass right next to the vertical
wire in four equidistant locations relative to the north-south alignment. For
all four locations, rotate the compass until its north axis aligns with the
compass needle pointer. The compass shown in the setup is a sample first
location.
3. Close the switch long enough for making observations.
4. Observe and draw the deflection (direction and rotation) of the compass
needle’s north-pole.
5. Open the switch when you are done with your observations.
6. Move the compass to the next locations to map the magnetic field. Do steps
2 to 5 for each of the remaining chosen locations.
7. Draw a short arrow to indicate the compass needle’s direction and rotation
in each of the four locations.
8. Reverse the polarity of your power supply and do steps 2 to 7.

112
Guide Questions:
Q27. From a top-view perspective, in what direction does the north pole
of the compass needle point to when the compass was positioned
around the vertical current-carrying straight conductor?
Q28. From a top-view perspective and with the current’s polarity
reversed, in what direction does the north pole of the compass
needle point to when the compass was positioned around the
vertical current carrying straight conductor?
PART B. Magnetic Field around a Coil of Conductor
1. Prepare a compass holder for the larger magnetic compass using a squared
rubber mat similar to what is shown in Figure 10. Trace the perimeter of a
3-4 cm wide magnetic compass on a used rubber mat. Safely cut a hole
on the mat that is big enough for the compass to fit into. Insert the compass
into the hole with the north-south alignment parallel to any side.
Figure 10. Coil of wire around a compass fitted into a used rubber mat
2. Strip the ends of a 1.5 meter long magnetic hook wire (#22 gauge and
stranded) and wind this around the compass on its holder. For easier
observations, loop the wire parallel along the north-south axis although the
loops can also be oriented perpendicularly. Slowly rotate the rubber mat
until the needle points north.
3. Connect the looped wire around the compass to a 3-volt power supply that
is in series to the open knife switch and the fuse as shown in Experiment
Setup B below.

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Experiment Setup B:
4. Close the switch long enough for making observations.
5. Relative to the geographic north-south alignment, observe and draw the
deflection (direction and rotation) of the compass needle’s north-pole.
6. Open the switch when you are done with your observations.
7. Reverse the polarity of your power supply and do steps 4 to 6.
8. Reduce to half the number of loops around the compass and cut the
excess making sure the loops are centered round the compass. Repeat step
3 to 6.
Guide Questions:
Q29. With conventional current flowing counterclockwise, from a top-
view perspective, in what direction does the north pole of the
compass needle, at the center of the current-carrying coil of wire,
point?
Q30. With conventional current flowing clockwise, from a top-view
perspective, in what direction does the north pole of the compass
needle, at the center of the current-carrying coil of wire, point when
the current’s polarity was reversed?
Q31. How will you compare the magnitude of the compass needle
deflections for the different number of loops in the current-carrying
coil?

114
Q32. If you will straighten the shortened coil of wire, how will you
compare the magnitude of the compass needle deflection at the
center of the previous current-carrying coil, to the compass needle
deflection near the just straightened current-carrying conductor?
Why?
9. Extending Inquiry – A solenoid (a coil of wire in which the length is greater
than the width) was made using a 3-meter long magnetic wire wound
clockwise from left to right around the iron rod. Current was then made to
flow through it using a circuit similar to what is shown to Figure 11 a.
Q33. What would be the direction of the magnetic field around the
current-carrying solenoid when the switch is closed?
Q34. Using arrows, draw the magnetic compass needle directions at
the indicated locations in Figure 11b. Then indicate which ends of
the solenoid acts similar to the north and south poles of a bar
magnet.
Figure 11. Checking the Magnetic Field around a Current-carrying Solenoid
FORCE ON A CURRENT-CARRYING WIRE IN A MAGNETIC FIELD
A non-magnetic current-carrying wire within a strong magnetic field,
like copper for instance, will experience a magnetic force as indicated by
the wire’s movement relative to the magnetic field. This turning effect on
a coil is used in ammeters and motors that use permanent magnets and
electromagnets.
Do the next activity and try to understand the interaction between the
magnetic field of the permanent magnet and the magnetic field due to the
current in the conductor.

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Activity 9
Making Your Own Electric Motor
Adapted from http://www.instructables.com/id/How-to-Make-a-Homopolar
Objectives:
• Build a simple electric motor.
• Explain the operation of a simple electric motor.
Materials:
• 1 AA battery
• 3 Neodymium magnets, 1/2” – 3/4”
• pliers or long nose
• AWG #14 – 18 solid and bare copper wire (~30 cm)
Figure 12. Materials for making an electric motor.
Safety Precautions:
• The neodymium magnet is many times stronger than the ordinary disk
magnet that can hold papers on refrigerator doors. Be careful not to
get your fingers pinched between these magnets and other magnetic
materials.
• Wires can get hot when connected to the battery for a long time. Open
the circuit once you are done with your observations.
Procedure:
1. Assembly of the Electric Motor Model – Cut the length of copper wire into
three pieces. With the use of the pliers, shape the three wires into a spiral,
square, heart or any figure to your liking similar to what is shown in Figure
13.

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http://ideas-inspire.com/simple-electric-motor/
Figure 13. A sample electric motor model using neodymium magnets.
2. Make a sample pile of the three neodymium magnets, the battery and the
shaped copper wire. Make adjustments to the length and width of the shaped
wire. See to it that there is a bare connection between the wire ends and
the neodymium magnet and also between the pivot part (balancing point)
of the wire and the positive terminal of the battery. Scrape or sand off the
material insulating the wire at these indicated points. Disassemble the set
up when making the needed shape adjustments and sanding of the copper
wire.
3. Testing of Model – Carefully pile with the three neodymium magnets and
the battery on a level surface. Mount the shaped wire, with its pivot part
as a rotating point, over the positive terminal of the battery. Check that the
bottom ends of the wire curl loosely around the magnets forming a closed
circuit. You now have a simple DC electric motor model that we will simply
call a DC motor model. Give the current-carrying shaped wire a gentle spin.
4. Observe and record what happens to the shaped wire. Warning! Disconnect
the DC motor model immediately after making observations.
5. If your DC motor does not work, stretch your tolerance, abilities, and
knowledge. Have fun making your motor model demonstrate the effect of
an electromagnetic force on a conductor that is within a magnetic field.
Guide Questions:
Q35. What happens to the shaped wire once positioned over the
battery’s positive terminal and with both wire ends curled loosely
touching the magnets?
6. Extending Inquiry of Model – Tinker with your electric motor model and try to
look for other ways to demonstrate the same effect by an electromagnetic
force.

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Q36. What other observations have you made regarding your electric
motor model?
Q37. What will happen if the number of neodymium magnets used in the
model is reduced? Increased?
Q38. What are the basic parts/elements of a simple electric motor?
Q39. Based on the activity, how will you explain the operation of a simple
electric motor?
ELECTROMAGNETIC INDUCTION
Now the basic parts of a DC motor can also be assembled to operate as
a DC generator. What would happen if instead of causing a current-carrying
conductor to move within a magnetic field, the closed circuit conductor is
mechanically moved within a magnetic field?
The next activity will enable you to explore and appreciate the Earth’s
magnetic field and its effect on a moving giant coil. Jump in for a simple yet
electrifying experience!
Activity 10
LET’S JUMP IN!
(Adapted from cse.ssl.berkeley.edu/.../lessons/...electromagnetism/mag_electromag.pdf‎)
Objectives:
• Observe the deflection of a galvanometer needle when an electrical
cord crosses the Earth’s magnetic field.
• Measure and record the magnitude of the deflection of the
galvanometer needle when the electrical cord is rotated:
a) slowly; c) when aligned east to west; and
b) quickly; d) when aligned north to south.
• Explain the operation of a simple electric generator.
Materials:
• 10 to 20 meters flat wire (double wire, stranded) AWG #22
• two lead wires with alligator clip on at least one end
• level field or ground (at least 6 meters x 6 meters)
• micro-ammeter or galvanometer
• pliers or long nose
• one compass

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Safety Precautions:
• A galvanometer is a very low resistance instrument used to measure
very small currents in microamperes. It must be connected in series
in a circuit. Use the galvanometer with care and without dropping it.
• Jump in safely and observe taking turns.
Procedure:
1. Strip off at least 1” insulation on all ends of the 20 meter flat wire. Loop the
stranded wires together for each end. Connect the ends of the jump wire to
the terminals of the galvanometer using the connecting wires with alligator
clips.
Figure 14. Generation and detection of electricity using the Earth’s magnetic field and rotating
loop of conductor connected in series to a galvanometer
2. Lay the loop of wire together with the galvanometer on the ground. This
long loop of cord-galvanometer arrangement will serve as the closed circuit
jump rope electric generator. The galvanometer will serve as detector of
the electric current that may be generated due to the Earth’s magnetic field
and other essential components for electricity.
3. As shown in Figure 14, have members of your group stand on the jump rope,
one at the far end and two near the galvanometer to secure the connections
and directional marks for the chosen rotation alignment. If possible secure
the connections and alignment another way, so everyone gets to observe
the galvanometer freely as the cord is rotated during the jumping activity.
4. Align the jump wire electric generator in any of the geographical directions:
(a) east to west, (b) north to south, and (c) northeast-southwest directions
using a compass as shown in Figures 15 and 16.

119
5. With half of the loop on the ground, have two group members on each end
pick up the free length of cord and rotate it clockwise or counter clockwise
(relative to the galvanometer end) like a jump rope as shown in Figure 14 .Take
turns rotating the cord and checking the galvanometer, even jumping in for
fun during the activity.
Figure 15. The galvanometer and jump wire electric generator set up along the East-West (left)
and along the North-South (right) alignments.
6. Try also rotating both half-lengths of the loop together and observe also the
galvanometer reading.
Figure 16. The galvanometer and jump wire
electric generator set up along the Northeast-
Southwest alignment
Figure 17. when both half-lengths of the
loop are rotated together
7. This time try to generate, measure, and record the electric current readings.
In doing so try to vary the following:
A. Speed of rotation.
B. Geographical alignment of rotation.
C. Direction of single-length loop rotation.
D. Length of rotated part.
E. Single or double half-length rotations.

120
8. Design and write your own graphic organizer for your observations on your
science notebook.
Guide Questions:
Q40. What effect does the rotating part of the loop have on the needle of
the galvanometer?
Q41. What effect does the speed of the rotating loop have on the
generated electric current?
Q42. Which condition or its combination would result to the greatest
generated electric current? Smallest current? No current
reading?
Q43. Why does the geographical alignment of the rotating jump wire
affect the galvanometer reading?
Q44. What are the basic components of the jump wire electric generator?
Q45. How will you explain the operation of a simple electric generator?
9. Extending Inquiry. Identify and describe the basic parts of the generator
model shown in the figure below.
Figure 18. DC Electric Generator
Q46. Which part/device shown in the figure above?
The activity on the jump wire generator operates using the principles of
electromagnetic induction. In this activity, it is the conductor that moves within
the Earth’s magnetic field. Will moving a source of magnetic field instead of the
conductor lead to the same findings?

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Activity 11
PRINCIPLES OF ELECTROMAGNETIC INDUCTION
(Adapted from the DepEd-NSTIC Activity on Faraday’s Induction)
Objectives:
• Observe the deflection of a galvanometer needle when a magnet
moves inside a current-carrying coil.
• Identify and explain the factors that affect the induced current through
a conductor.
Materials:
• 3.6 meters hook/connecting wires (about 20 fine strands along the
length of insulated magnet wire)
• tape measure
• size D dry cell
• sticky tape and pair of scissors
• galvanometer
• two wooden blocks
• two wires with alligator clips
• pair of bar magnets
Safety Precautions:
• A galvanometer is a very low resistance instrument used to measure
very small currents in microamperes. It must be connected in
series in a circuit with the pointer at the zero point mark. Use the
galvanometer with care so as not to drop it.
Procedure:
1. Using a size D dry cell as guide, wind a 5-turn, a 10-turn, and a 15-turn coil
out of a 60-cm, 120-cm and a 180-cm connecting wire respectively. Use
small pieces of tape to hold the coil together on two or three areas. Remove
the insulation from each end of the coil and strand the fine wires together
for easy connection.
2. Set up the galvanometer, wooden blocks and bar magnets as shown in
Figure 19.

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Figure 19. A simple electromagnetic induction activity set up with a galvanometer that has its
zero point mark in the center of the scale. This type of galvanometer measures the presence
of a very small current, its direction, and its relative magnitude.
Part A. Inducing voltage and current in a coil
3. As shown in Figure 20, lay the 5-turn coil above the two wooden blocks
and connect it ends to the galvanometer via wires with alligator clips. At
this point, observe what happens to the galvanometer pointer.
Figure 20. Move the north pole of a bar magnet into a 5-turn coil
4. Hold a bar magnet above the coil as shown in Figure 20. Move the north
pole of the magnet into the coil. Observe the galvanometer pointer as you
do this. On your science notebook, make a table similar to Table 10 and
record your observations.

123
Table 10. Inducing current in a coil
Condition
Coil
Without a
Magnet
Magnet is
Moving into
the Coil
Magnet is at
Rest Inside
the Coil
Magnet
is Moving
Out of the
Coil
Galvanometer
pointer’s
deflection or non-
deflection
Galvanometer
pointer’s
direction of
deflection
5. Hold the magnet inside the coil without moving it for a few seconds. Observe
what happens.
6. Pull the magnet out of the coil. Observe the galvanometer pointer as you do
this.
Q47. How will you explain the deflection or non-deflection of the
galvanometer pointer as observed in the activity?
Q48. How will you compare the directions of deflection? Why do you
think this is so?
Part B. Amount of induced voltage and current vs number of turns
7. Use the set up to explore the relative magnitudes of the galvanometer
pointer’s deflection for the 5-turn, 10-turn and 15-turn coils. Record your
observations on your science notebook.
Q49. For approximately the same speed of moving the magnet into or
out of each coil, what happens to the magnitude of the pointer’s
deflection as the number of turns in the coil increase?
Part C. Amount of induced voltage and current vs strength of magnetic
field
8. Use the 15-turn coil and the set up to explore the relationship between
the magnitude of the galvanometer pointer’s deflection and the magnetic
field strength using (a) one bar magnet, and (b) two bar magnets with like
poles held together in parallel. Record your observations on your science
notebook.

124
Figure 21. Move the north poles of two parallel bar magnets into a 15-turn coil.
Q50. For approximately the same speed of moving the magnet into
or out of the 15-turn coil, what happens to the deflection of the
galvanometer pointer as the number of bar magnets (strength of
magnetic field) increase?
Part D. Amount of induced current vs rate of magnetic field change
9. Use the 15-turn coil and a bar magnet to explore the relationship between
the magnitude of the galvanometer pointer’s deflection and the speed of
movement of the magnet into or out of the coil. Record your observations
on your science notebook.
Q51. What happens to the deflection of the galvanometer pointer as the
bar magnet is moved into or out of the 15-turn coil at different
speeds (rate of magnetic field change)?
Part E. Coil orientation and direction of magnetic field change
10. As shown in Figure 22, move (a) a bar magnet along one of the coils
(preferably the 15-turn) and observe the magnitude of the galvanometer
pointer’s deflection. Compare this deflection to that when (b) the bar magnet
moves across (into or out) the coil at approximately the same speed. Record
your observations on your science notebook.
Figure 22. The bar magnet is moved (a) along or parallel to the coil orientation, and (b) across
or perpendicular to the coil orientation

125
Q52. How would you compare behavior of the the galvanometer pointer
when the magnet moves along the coil and when the magnet
moves across the coil?
Q53. In your own words, what are the factors that affect the amount
of current and hence voltage (EMF) induced in a conductor by a
changing magnetic field?
Q54. An equation for the electromagnetic force (EMF) induced in a
wire by a magnetic field is EMF = BLv, where B is magnetic
field, L is the length of the wire in the magnetic field, and v is
the velocity of the wire with respect to the field. How do the
results in this activity support this equation.
11. Extending Inquiry. The principle of electromagnetic induction in two nearby
coils can be demonstrated by a transformer. A typical transformer has two
coils of insulated wire wound around an iron core. This device changes
the AC voltage of the primary coil by inducing an increased or decreased
EMF in the secondary coil. In practical applications, why does this device
operate only on alternating current and not on direct current?
Additional Reading
Speed Control Technology – To ensure road safety and minimize
vehicular-related death, buses, and other public utility vehicles can be equipped
with a speed control device that limits the maximum speed by using electro-
magnetic brakes in combination with a motor once the limit is exceeded.
Speed control motor packages include the motor, the driver (controller),
and a potentiometer which allows the driver for easy speed control adjustment.
When the speed of this motor is controlled, a tacho-generator connected to the
motor detects the speed. It is a magnet connected directly to the motor shaft
and stator coil. The stator coil detects the magnetic field and generates an
alternating current (AC) voltage.

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Figure 23. Motor speed control technology diagram
Since this voltage and frequency increase with a rise of the rotational
speed, the rotational speed of the motor is controlled based on this signal.
Traffic Light – Vehicles waiting at intersections with coils buried underneath
is within an electromagnetic field. Changes in the field activate the traffic light as
programmed.
Typical red-light traffic systems have two induction-loop triggers made
of rectangular or concentric wire loops buried under the road close to the stop
line. This wire is connected to an electrical power source and a meter.
Figure 24. An induction-loop traffic system at a road intersection senses vehicles within its
electromagnetic fields
The current through the wire produces a magnetic field affecting objects
around the loop and the loop itself. When there is another conductive material
within the magnetic field, then a changing induced voltage is detected. This
results to changing magnetic flux that triggers the traffic system according to its
programmed mechanism.

127
Metal Detector – Metal detectors trigger the “Bleep! Bleep! Bleep!” sound
when objects with parts that are magnetic in nature move past it. This signal a
precious find, a hidden unwanted object or a need for further security check.
Figure 25. A basic pulse-electromagnetic induction metal detection technique
The transmitter coil is given a pulsed current long enough for the
transmitter’s magnetic field to reach the metal target. The transmitter’s loop
current is then turned off. The changing or collapsing magnetic ﬁeld induces
an electromotive force that induce charges to flow in the metal target. This
induced current creates a reradiated magnetic field that can be detected by a
receiver coil located at the sensor.
In some metal detectors, it is the device that is moved over the object.
In other detectors, it is the object or the person that moves pass the machine.
Whatever is the case, the current-carrying transmitting coil creates a changing
magnetic field which in turn creates a changing electric field that creates the
secondary magnetic field detected by the receiver coil.
Induction Stove – Food cooks faster when heat is conducted directly
and almost entirely at the base of the cooking pot. In induction stoves, current
flowing through the copper coil wound underneath the cooking surface produces
an electromagnetic field small enough to surround the base of the cooking pot.
The magnetic field induces an electric current within the base of the metal pot.
The metal in the cookware has electrical resistance that opposes the induced
current and causes friction for the pot to heat up.
Data acquisition and
control system
ReceiverPulse transmitter
Transmitter
magnetic field
transmitter coil Receiver coil
Reradiated
magnetic field
induced current on
metal targer

128

Figure 26. Induction stove working mechanism
Heat transfer in an induction stove is more efficient than that via the gas
stove because almost all of its heat is conducted directly to the base of the pot
unlike in gas stoves where much heat escapes around the side and heats up
the room and the rest of the cooking pot.
Figure 27. In induction cooking, heat loss is lesser than in gas cooking
Magnetic Recording – Computer working memories (RAM’s and
ROM’s), mass storage memories (magnetic hard disks, floppy disks, magnetic
tape drives, and optical disk drives), and practically all write-able card storage
devices (magnetic cards, smart cards, and flash memory cards) make use of
the magneto-optical characteristic of the recording media to store information.
Figure 28. Read/Write Head of a Disk Player
How Induction Cooking Works
metal pot
Water
electromagnetic
field
current-carrying
copper coil
Head Drum
Take Up
Video Tracks
TapeSupply
Read/ write Head
Disk motion
Substrate
Gap
coil
Read/Write Head
core
Magnetized (aligned)
media particles Random (non-aligned)
media particles Media
coating

129
Performance Task
An Octo Challenge Audio-Visual Presentation (AVP)
Using Electromagnetic Induction (EMI)
An Enrichment Activity
Objective:
Plan, perform, and record a 5-minute audio alone or audio-visual
presentation related to any Philippine National Celebration during
October using devices that apply both electricity and magnetism.
Materials:
• at least one musical instrument
• audio alone or audio-video recording technology of your choice
• support materials as needed by your team
• printed transcript of spoken parts of AVP
Procedure:
1. Meet as a group and agree on the role of each member according to interests
and skills in the making and recording of the AVP presentation.
2. Listed are eight October national celebrations observed by Filipinos:
• National Children’s Month • Elderly Filipino Week
• Philippine Consumer Welfare
Month
• Food Safety Awareness
Week
• Moral Guidance Week for
Public Servants
• United Nations Celebratio
• Indigenous People’s
Celebration
• World Teacher’s Day
Use only one event to highlight in your AVP tribute that will introduce briefly
the audience to the making and recording of an audio-only or an audio-
visual presentation using electromagnetic induction partially or entirely.
3. Your group has four weeks to plan, perform and record together the five-
minute AVP tribute with the following guidelines:
a) Gather information about your selected musical instrument and
recording device. Learn how these use electricity and magnetism. Give
a multimedia introduction on this for a minute or two.
b) Dedicate the remaining three minutes in highlighting the chosen October
event. Decide whether you will record an audio-only or an audio-visual

130
presentation taking into consideration the listening and processing
efforts needed to fully appreciate the event or the reason behind it. Plan,
perform and record an age-appropriate music-video tribute.
c) Ensure that the AVP is an output of the whole circle of friends. At the end
of the AVP include a brief roll of credits.
d) The making and recording of the AVP should be done only during non-
class hours inside the school premises only.
e) You are liable for the proper and safe use of all audio-video production
and recording devices whether these are personally owned or a school
property. Ensure also minimal energy use.
f) Agree on a checklist to help your group monitor your task progress.
Prepare also a written transcript of your AVP’s recorded audio.
g) Prepare a digital record of your AVP on a compact disc, ready for
premiere viewing in the class at the end of this module period.
Criteria for Success - The making and recording of the October-themed AVP
will be rated based on the following criteria:
1. Knowledge and understanding of EMI.
2. Thinking and inquiry on the AVP plans and preparations.
3. Communication through language and style.
4. Communication through music and video presentation conventions.
5. Special Criterion on Technical Quality or Original Song Production.
Ask your teacher for this task’s GRASPS guidelines to help your group in
the successful completion of the performance task before the end of Module 1.
Refer also to the corresponding performance task rubric for the Development
of an Octo Challenge Audio-Visual Presentation as you assess your group’s
progress.
Your teacher will also use the same rubric in assessing your performance,
content, and product-wise.

131
V. Summary/Synthesis/Feedback
• Many of the audio-video recording technology apply the relationship between
electricity and magnetism known as electromagnetic induction.
• A typical recording studio consists of an audio-video console, microphones,
computers, studio monitors or speakers, disc players and cables used for
the exchange of audio and digital data signal during production, recording,
mixing, and even editing of all audio-video elements digitally stored on disk
drives.
• Devices that detect and convert audio inputs to electric outputs or vice versa
are called transducers. Most transducers like microphones and speakers use
the “generator effect” characterized by the production of electromotive forces
due to either a changing electric signal within a magnetic field or a changing
magnetic field near a current-carrying conductor.
• Magnetism is commonly attributed to ferromagnetism and electromagnetism
depending on the material and moving charges. Every atom and all moving
charges are in constant motion and therefore has a bit of magnetism due to
magnetic spins and domains creating a net magnetic field.
• A magnet has two magnetic poles (north and south seeking poles).
• Stroking with a permanent magnet is one of the ways to induce or cause
magnetism in an object that can be magnetized. The polarity of the induced
magnetism in the object is opposite to the polarity of the nearer end of the
permanent magnet. Attraction happens after magnetic induction occurs.
• A magnet attracts, but do not repel, unmagnetized ferromagnetic materials
such as iron, nickel, cobalt and some of its alloys like steel and alnico.
• Both forces of attraction and repulsion is possible between magnets and
between a magnet and a temporarily magnetized object.
• A magnetic field surrounds a magnet. Within this region, the magnet affects
another magnet and other objects that can be magnetized.
• The magnetic field is strongest at the poles where the magnetic lines of
induction (flux) are closest. The magnetic field pattern can be shown using
iron filings that align along magnetic lines of induction.
• The magnetic lines of induction leave the north-pole and enter the south-pole
in close loops and can be indicated by the north pole of a compass.

132
• The loops of magnetic field lines between like poles bend away from each
other showing a force of repulsion. The lines between unlike poles join with
each other to form continuous lines showing a force of attraction.
• The earth acts like a giant bar magnet and has a magnetic field similar to it.
• A charge has an electric field around it where other charges will experience
an electromagnetic force. Like charges repel while unlike charges attract.
• Moving charges or current in a wire produces a magnetic field.
• An electromagnet is a coil of wire that uses current to produce a strong
magnetic field.
• The magnetic field patterns of a disk magnet, an electromagnetic nail, a
current carrying straight conductor, and a current carrying coil are similar to
that of the single bar magnet.
• The magnetic field pattern between the poles of a U-shaped magnet resembles
the field pattern between unlike poles of two bar magnets. Compasses aligned
along the magnetic field show that the lines point from the north to the south
poles and back forming close loops.
• If the two bar magnets with two unlike poles which are close in between is
brought together, the magnetic field pattern will resemble that of the single
bar magnet. Lines from one pole enter the other pole.
• Most refrigerator magnets has a pattern of alternating bands of magnetic field.
• If the direction of the current is known, the direction of the magnetic field that
is perpendicular to it and the magnetic force that is perpendicular to both
current and magnetic field can be determined by applying the hand rules.
• Using the right hand rule, the direction of the magnetic field follows the
direction of the right hand fingers when the right thumb points in the direction
of the conventional current (from positive to negative).
• Using the left-hand rule, the direction of the magnetic field follows the direction
of the left hand fingers when the left thumb points in the direction of the real
flow of current (from negative to positive).
• The magnetic field is strongest at the center of a current-carrying coil.

133
• The magnetic field increases in direct proportion to the number of turns in a
coil with the compass needle, at the center of the coil of wire, deflecting about
a wider angle than the compass needle along the straightened wire.
• The end of the current-carrying coil where the magnetic lines of induction
come out acts as the north pole of the coil.
• A magnetic field exerts a force on a current-carrying conductor. Using the
right-hand rule, the direction of this force is in the direction where the palm
faces.
• The motor effect is shown when a current-carrying conductor within a magnetic
field moves in the direction of the force. The force on a moving current-
carrying conductor may be varied by changing the magnetic field.
• An electric motor is a device that converts electrical energy into rotational
mechanical energy. A simple DC motor can be assembled using a single
coil that rotates in a magnetic field. The direct current in the coil is supplied
via two brushes. The forces exerted on the current-carrying wire creates a
rotation-causing force on the coil.
• An electric generator is a device that converts mechanical energy into
electrical energy. A simple electric generator is made when a coil or any
closed loop of conductor moves through or cuts across magnetic field lines.
The coil will experience an induced voltage or an electromotive force that will
cause a pulsating direct current (DC) to be generated. The pulsating direct
current fluctuates in value but does not change direction.
• Electromagnetic induction is a process in which electric current is generated
in a conductor by a moving or changing magnetic field.
• A changing magnetic field occurs when there is relative motion between a
source of a magnetic field and a conductor; it does not matter which moves.
• A changing magnetic field may also arise from a changing nearby current.
• The amount of voltage (EMF) induced when a conductor and a magnetic field
are in relative motion depends on (a) the length L of the conductor or the
number of turns in the coil, (b) the strength and orientation of the magnetic
field B relative to the conductor, and (c) The relative velocity v of the changing
magnetic field.

134
• The equation for the induced voltage or electromagnetic force (EMF) in a wire
by a changing magnetic field is EMF = BLv. By Ohm’s Law the amount of
induced current is directly proportional to the induced voltage.
• A transformer uses electromagnetic induction in two nearby coils (the primary
and secondary coils). Typically, the two coils of insulated wire are wound
around an iron core. This device changes the AC voltage of the primary coil
by inducing an increased or decreased EMF in the secondary coil.
VI. Summative Assessment
Directions. Choose the letter of the correct answer.
1. In which case or cases is an electric field present?
I. A spark jumping between two nearby rods.
II. A charge that is momentarily at rest.
III.A dead power line.
a. I only
b. I and II only
c. II and III only
d. I, II and III
2. Which device can be used to determine the polarity of an unmarked magnet?
a. a suspended magnetized needle
b. an improvised magnetic board
c. a second unmarked magnet
d. a charged metal rod at rest
3. In which device is magnetic field present?
a. A charged balloon.
b. A cooling soldering iron.
c. A very hot horse-shoe magnet.
d. A microphone undergoing a sound check.
4. How will you describe the magnetic field around a current-carrying coil?
a. The magnetic field is weakest near and around the coil.
b. The magnetic field vary directly with the distance from the coil.
c. The magnetic field is strongest inside the current-carrying coil.
d. The magnetic field lines are closed loops along the loops in the coil.

135
5. Which statement about an electromagnetic nail is NOT TRUE?
a. Steady magnetic lines of induction surround a battery-powered
electromagnetic nail.
b. The current in the electromagnetic nail demagnetizes the iron nail.
c. The magnetic field lines produced resemble that of a bar magnet.
d. The magnetic field strength is proportional to the nail’s current.
6. What can be inferred from the alignment of compass needles around the
pick-up coil below?
a. Current is drawn into the coil.
b. A permanent magnet is nearby.
c. The DC power switch was turned off for long.
d. There is a uniform magnetic field around the coil.
7. What basic principle enables ALL electric generators to operate?
a. Iron is the only element that is magnetic.
b. Opposite electric charges attract and like charges repel.
c. A closed-loop conductor within a changing magnetic field will have an
induced electromotive force.
d. Acurrent-carryingconductorplacedwithinamagneticfieldwillexperience
a magnetic force.
8. Which of the following statements can be inferred from the main photo
above? (For easier inspection, a paper is inserted halfway between the
open disk tray and a magnetic board)

136
a. The iron filings inside the magnetic board is unaffected.
b. The CD-DVD disk tray uses a small permanent bar magnet.
c. The optical system has an electric motor that drives the reader.
d. The optical reader has a lens system that affected the iron filings.
9. Which arrangement of three bar magnets results to an attraction between
the first and the second, and a repulsion between the second and the third
magnet.
10. Complete the following statement: A metallic detector was used to check a
bag for metallic objects. The transmitter coil
a. A. draws a steady current to send a steady magnetic field towards the
target to induce current in it.
b. draws a pulsating current to send a steady magnetic field towards the
c. draws a steady current to send a changing magnetic field towards the
d. draws a pulsating current to send a changing magnetic field towards the
11. A coil moves away from a magnet. Consider the following factors:
I. strength of the magnet
II. number of turns in the coil
III. speed at which the magnet moves
Which can affect the electromotive force (EMF) induced in the coil?
a. I only
b. II only
c. III only
d. All three factors
a.
b.
c.
d.

137
12. Which set ups model the working principle of a transformer and an electric
generator respectively?
a. A and B b. B and D c. C and D d. D and A
13. Which statement is TRUE about the illustration below?
a. In set up A, the magnet is at rest inside the moving coil.
b. In set up B, the magnet is being pulled out of the moving coil with the
same speed.
c. There is relative motion between the magnet and coil in set up A.
d. There is relative motion between the magnet and coil in set up B.
14. What transformation can take place in a ceiling fan’s electric motor?
a. electrical energy into mechanical energy
b. mechanical energy into electrical energy
c. alternating current into direct current
d. direct current into alternating current

138
15. What is TRUE about the intercom system that is shown below?
a. The part A of the intercom system serves as a microphone only, while
part C serves as a loudspeaker only.
b. Either parts A and C of the intercom when switched as such can be used
as a microphone or as a loudspeaker.
c. The microphone part only basically consists of wires, a cone diaphragm,
a magnet, and a coil.
d. The loudspeaker part only basically consists of wires, a cone diaphragm,
a magnet, and a coil.
Glossary of Terms
Charged particles are sources of electric fields which result in an
attraction or repulsion of other nearby charges
Electric charge a fundamental electrical property that is either
of positive or negative type to which the mutual
attractions or repulsions between protons or
electrons is attributed
Electric field force field surrounding electric charges or group of
charges where a force acts on charges within the
field
Electric generator device that converts mechanical energy into
electrical energy usually by rotating a coil within a
magnetic field
Electric motor device that converts electrical energy into
mechanical energy using the magnetic turning
effect on a coil
Electricity produced by vibrating or flowing charges

139
Electromagnet magnet whose magnetic properties are produced
by electric current
Electromagnetic phenomenon of inducing a voltage in a conductor
induction by changing the magnetic field near the conductor.
If a magnetic field within a closed loop changes in
any way, a voltage or electromotive force is induced
(produced) in the loop
Electromotive force voltage that gives rise to an electric current
Galvanometer low resistance instrument used to measure
very small currents, its direction and its relative
magnitude
Magnet object that has the magnetic ability to attract objects
made of iron or other magnetic substance
Magnetic Domain microscopic grouping of atoms with their magnetic
field aligned
Magnetic field region of magnetic influence around the magnetic
poles and moving charged particles
Magnetic field lines lines showing the shape of a magnetic field. A
compass placed on such a line will turn so that the
needle is aligned with it because of electromagnetic
induction
Magnetic force between magnets, it is attraction of unlike magnetic
poles and the repulsion between like magnetic poles;
between a magnetic field and a moving charged
particle, it is a deflecting force due to the motion of the
particle; the deflecting force is perpendicular to both
the magnetic field lines and the direction of motion
Magnetic poles magnetic south or north seeking regions on a
magnet that produces magnetic forces
Magnetism property of being able to attract objects made of
naturally occurring magnetic substances like iron,
nickel, cobalt or some of its alloys
Transformer can step-up or step-down voltages using the
principles of electromagnetic induction

140
References and Links
Printed Materials:
Department of Education - National Science Teaching Instrumentation Center
(n.d.). User’s Laboratory Manual for Physics - Student Worksheets for
Secondary School Physics. Lahug, Cebu: NSTIC.
Glencoe Physics Principles and Problems: Laboratory Manual. (Teacher ed.).
New York, NY: Mc Graw-Hill Companies.
Hewitt, Paul G. (2006). Conceptual Physics, (10th ed). Menlo Park, California:
Addison Wesley Publishing Inc.
Higgins, C. Jr., Shipman, J., Wilson, J. (2013). An Introduction to Physical
Science. Pasig City: Cengage Learning Asia Pte. Ltd.
Littell, M. (2005). Science Integrated Course 2. Teacher’s Edition. Evanston,
Illinois: McDougal Littell.
Loo, K. W., Loo, W.Y., See, T. W. (2004). Physics Insights. Philippines: Pearson
Education Asia Pte. Ltd.
Pople, S. (1999). Co-ordinated science: Physics. Walton St., Oxford: Oxford
University Press.
Robinson, P. (2002). Conceptual physics: Laboratory manual. Upper Saddle
River, NJ: Prentice-Hall, Inc.
University of the Philippines - National Institute for Science and Mathematics Education
Development. (2007). Practical work in high school physics -Asourcebook for
teachers. (2nd ed.). Diliman, Quezon City: UP-NISMED Press.
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control geomagnetic reversal frequency. Geophysical Research Letters.
[Accessed: October 29, 2014 2:23 A.M.] at http://www2.cnrs.fr/en/1923.
htm
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[Accessed: November 1, 2014]
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http://education.mrsec.wisc.edu/background/fridgemag/ [Accessed: July 26, 2014]
http://jedsound.com/blog/wp-content/uploads/2010/09/spk.png
[Accessed: March 4, 2014]

141
http://knowhow.com/article.dhtml?articleReference=1118&country=uk
[Accessed: October 29, 2014]
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[Accessed: March 5, 2014]
http://lifehacker.com/5853193/how-can-i-set-up-a-home-recording-studio-on-
the-cheap [Accessed: March 1, 2014]
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http://phet.colorado.edu/en/get-phet/full-install (Jan 21, 2015 version)
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[Accessed: February 27, 2014]
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awareness-mcqs.html
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magnetic_field.org

142
I. Introduction
In Module 1, you have learned about the interrelationship between
electricity and magnetism. You were able to discover how electric field could
create magnetic field and vice versa.
In this module, you will learn about the different regions of the
electromagnetic spectrum. This module will lead you to understand how
electromagnetic waves transport energy. It also consists of activities that will
enrich your understanding on the application of electromagnetic waves in our
everyday living, and consequently, how these waves affect living things and the
environment.
At the end of Module 2, you will be able to answer the following questions:
1. Trace the development of the electromagnetic theory.
2. Describe how electromagnetic (EM) wave is produced and propagated.
3. Compare the relative wavelengths, frequencies and energies of the
different regions of the electromagnetic spectrum.
4. Cite examples of practical applications of the different regions of EM
waves.
5. Explain the effects of electromagnetic radiation on living things and the
environment.
ELECTROMAGNETIC
SPECTRUM
1. How do the regions in the electromagnetic spectrum differ in terms
of wavelength, frequency and energy?
2. How do the different types of electromagnetic waves become
relevant to people and environment?
3. What are the consequent effects of electromagnetic waves?
Unit 2
MODULE
2

143
III. Pre-Assessment
A. Choose the letter of the correct answer.
1. Which two waves lie at the ends of the visible spectrum?
a. Infrared and Ultra-violet rays
b. Radio waves and Microwaves
c. Radio waves and X-rays
d. X-rays and Gamma rays
2. In the visible spectrum, which color has the longest wavelength?
a. Blue b. Green c. Red d. Violet
3. Which property spells the difference between infra-red and ultra-violet
radiation?
a. Color
b. Speed in vacuum
c. Wavelength
d. None of the above
4. A certain radio station broadcasts at a frequency of 675 kHz. What is
the wavelength of the radio waves?
a. 280 m
b. 324 m
c. 400 m
d. 444 m
5. What type of electromagnetic waves is used in radar?
a. Infrared rays
b. Microwaves
c. Radio waves
d. Ultra-violet rays
B. Below are the applications of electromagnetic waves. State the type
of electromagnetic wave used in each application.
1. Camera autofocusing
2. Radio broadcasting
3. Diagnosis of bone fractures
4. Sterilization of water in drinking fountains
5. Sterilization of medical instruments
C. Answer the following question briefly but substantially.
1. How are EM waves different from mechanical waves?
2. Give two sources of EM waves in the Earth’s environment.

144
The Electromagnetic Wave Theory
Did you send text messages to somebody today? Or have you ever tried
cooking in a microwave oven? Did you know that these previously mentioned
human activities make use of microwaves? Microwaves carry energy, and so
with the other kinds of electromagnetic waves. But what are electromagnetic
waves? How can these waves become useful to us?
For a start, let us learn how the study of the electromagnetic waves
came to be.
The research work enabled you to gain information about the scientists
who made great contribution to the development of the electromagnetic theory.
Your gathered information will be useful in accomplishing the first activity.
Activity 1
How it came about…
The Electromagnetic Wave Theory
(Adapted from APEX Physics LP Chapter 3 Lesson 3: Student Activity 3a: The
Electromagnetic Theory)
Objectives:
• Match the scientists with their contributions to the development of
the electromagnetic theory.
• Make comic strips of the scientists’ contributions.
Materials:
• 1 white cartolina
• 1 marker pen
• 1 pencil with eraser
• coloring materials (optional)
Agreement:
Do a research to find out who were the proponents on the formulation of
electromagnetic theory. You may use print and non-print references to
gather your information. You may limit it to 5 significant scientists. Be sure
to indicate your sources/references for proper acknowledgment.

145
Procedure:
I. Match the scientists given below with their contributions.
Scientists Contributions
______1. Ampere a. Contributed in developing equations that
showed the relationship of electricity and
magnetism
______2. Faraday b. Showed experimental evidence of
electromagnetic waves and their link to
light
______3. Hertz c. Demonstrated the magnetic effect based on
the direction of current
______4. Maxwell d. Formulated the principle behind
electromagnetic induction.
______5. Oersted e. Showed how a current carrying wire
behaves like a magnet
II. Using the information you gathered previously, make a concept web/
comic strips of the contributions of the following scientists.
A. Ampere
B. Faraday
C. Hertz
D. Maxwell
E. Oersted
Guide Questions:
Q1. What new insights/learning did you get about our natural world?
How did it change your view about light?
You are about to explore the unknown world of EM spectrum. Read
and research for more scientists who made significant contributions in the
development of the study on the EM spectrum.

146
The Electric and Magnetic Fields Together
Accelerating electrons produce electromagnetic waves. These waves
are a combination of electric and magnetic fields. A changing magnetic field
produces an electric field and a changing electric field produces a magnetic
field. As accelerated electrons produce an electric field of a wave, the varying
electric field produces the wave’s magnetic field. Both the electric field and the
magnetic field oscillate perpendicular to each other and to the direction of the
propagating wave.
Figure 1. Electromagnetic Wave
All electromagnetic waves can travel through a medium but unlike other
types of waves, they can also travel in vacuum. They travel in vacuum at a
speed of 3X108
m/s and denoted as c, the speed of light. The wave speed,
frequency, and wavelength are related by the following equation:
v=λf
where v is the wave speed, or c (speed of light) expressed in meters
per second, the frequency f is expressed in Hertz and the wavelength λ is
expressed in meters.
Since all the EM waves have the same speed and that is equal to the
speed of light, as wavelength decreases, the frequency of the wave increases.
Through the years, the advancement on the knowledge about
electromagnetic waves led us to a modern technological world.

147
Example Problems:
(Assume that the waves propagate in a vacuum.)
1. What is the frequency of radio waves with wavelength of 20 m?
Given: v= c = 3X108
m/s
λ= 20 m
f= ?
v=c=λf
f=c/λ
= 3X108
m/s
20 m
= 1.5 X107
Hz
2. What is the frequency of light waves with wavelength of 5 X 10-7
m?
Given: v= c = 3X108
m/s
λ= 5 X 10-7
m
f= ?
v=c=λf
f=c/λ
= 3X108
m/s
5X10-7
m
= 6 X1014
Hz
Check your understanding!
Are these statements true? If not, correct them.
1. Electromagnetic waves transfer energy through vacuum.
2. A wave is a disturbance that transfers energy.
3. Most EM waves are invisible and undetectable.
The Electromagnetic Spectrum
The electromagnetic spectrum is a continuum of electromagnetic waves
arranged according to frequency and wavelength. It is a gradual progression
from the waves of lowest frequencies to the waves of highest frequencies.
According to increasing frequency, the EM spectrum includes: radio waves,
microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. These
waves do not have exact dividing region.

The different types of electromagnetic waves are defined by the amount
of energy carried by/possessed by the photons. Photons are bundles of wave
energy. The energy of a photon is given by the equation:
E=hf
where h is the Planck’s Constant and f is the frequency of the EM wave. The
value of the Planck’s constant is 6.63 x 10-34
joules per second.
From among the EM waves, the gamma rays have photons of high
energies while radio waves have photons with the lowest energies.
With regards to wavelength, radio waves can be likened to the size of a
football field while gamma rays are as small as the nuclei of an atom.

148
Figure 2 will give you a clearer idea of the characteristics of the
electromagnetic waves as their sizes are compared with visible materials.
Figure 2. The Electromagnetic Spectrum

149
Table 1 shows the relative wavelength, frequency, and energy of each
of the different types of electromagnetic waves.
Table 1. The electromagnetic waves’ wavelengths, frequencies, and energies
EM Wave Wavelength (m) Frequenzy (Hz) Energy (J)
Radio > 1 x 10-1
< 3 x 109
< 2 x 10-24
Microwave 1 x 10-3
-1 x 10-1
3 x 109
- 3 x 1011
2 x 10-24
- 2 x 10-22
Infrared 7 x 10-7
- 1 x 10-3
3 x 1011
- 4 x 1014
2 x 10-22
- 3 x 10-19
Visible 4 x 10-7
- 7 x 10-7
4 x 1014
- 7.5 x 1014
3 x 10-19
- 5 x 10-19
UV 1 x 10-8
- 4 x 10-7
7.5 x 1014
- 3 x 1016
5 x 10-19
- 2 x 10-17
X-ray 1 x 10-11
- 1 x 10-8
3 x 1016
- 3 x 1019
2 x 10-17
- 2 x 10-14
Gamma-ray < 1 x 10-11
> 3 x 1019
> 2 x 10-14
After learning about the wavelengths and frequencies of the different
types of EM waves, try this next activity to learn more on other characteristics
of EM waves.
Activity 2
Now you go! Now you won’t!
Adapted from: http://www.sciencebuddies.org/
Objectives:
• Identify materials that can block or allow radio waves to pass through.
• Compare the speed of EM waves through different materials.
Materials:
Remote controlled (RC) Car and controller (both with new batteries)
Different materials to test:
• Aluminum foil
• Plastic wrapper
• Paper
• Wax paper
• Cotton
• Rubber gloves
A wide open space to test drive your RC car.
Procedure:
1. Wrap the antenna of the RC car and of the receiver with the first
material you want to test, using several layers so that they are
completely and securely covered.
2. Attempt to operate the RC car using the remote control. Does it work?

150
3. Use a stopwatch to time your test drive over a set distance.
4. Repeat steps 1 to 3 using other materials. Make sure to maintain the
distance between the RC car and the remote control. Collect data in
a table similar to the table below.
Set Distance: _______________
Material Does the
car work?
(Y/N)
Time of
Travel
Observations
aluminum foil
plastic wrapper
paper
wax paper
cotton
rubber glove
5. Divide the materials into good and poor transmitters based on your
results.
Guide Questions:
Q2. Compare the time taken by the RC car to cover the same distance.
Do some go faster or slower?
Q3. What does this tell you about the transmission of the signal?
Q4. What characteristic of EM waves did you discover?
Radio Waves
Radio waves have the longest
wavelength in the electromagnetic
spectrum. They are produced by
making electrons vibrate in an
antenna. They are used to transmit
sound and picture information over
long distances.
Figure 3. A radio

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Radio waves have a very wide range of wavelengths. The whole
region of the radio waves is divided into smaller regions or wavebands. Each
waveband is allocated by law to a specific radio service. The wavelengths and
frequencies of the different wavebands and their uses are shown in Table 2.
Table 2. Radio waves Frequencies
BAND Frequency
Range
Wavelength
Range
Application
Extremely Low
Frequency (ELF)
< 3 kHz > 100 km
Very Low
Frequency (VLF)
3-30 Hz 10-100 km
Low Frequency
(LF)
30-300 kHz 1-10 km Radio communication
Medium
Frequency (MF)
300 kHz – 3
MHz
100m – 1 km Radio communication
(AM radio broadcasting)
High Frequency
(HF)
3 – 30 MHz 10 – 100 m Radio communication
(AM radio broadcasting)
Very High
Frequency (VHF)
30 – 300 MHZ 1 – 10 m Radio communication
(FM radio broadcasting)
TV Broadcasting
Ultra High
Frequency (UHF)
300 MHz – 3
GHz
10 cm – 1 m Radio communication
(FM radio broadcasting)
TV Broadcasting
Super High
Frequency (SHF)
3 – 30 GHz 1 – 10 cm Radio communication
Satellite Communication
Extremely High
Frequency (EHF)
30 – 300 GHz 1mm – 1 cm
Low frequency waves are suitable for communication over great
distances. But the curvature of the earth limits the range to about 80 kilometers.
To extend the range, a repeater is used. The repeater receives the signal and
re-transmits it to the receiving station.

High frequency waves can be reflected by the ionosphere. This enables
the waves to be transmitted over great distances.

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Medium and high frequency waves are used for broadcasting by local
radio stations. In a radio station, sound is converted by a microphone into
patterns of electric current variations called audio-frequency (AF) signals. High
frequency radio waves called radio-frequency (RF) carriers can be modulated to
match the electronic signal. In amplitude modulation, the amplitude of the radio
waves (RF carrier) changes to match that of the audio-frequency signal. This
is used in standard broadcasting because it can be sent over long distances.
Very high frequency waves provide a higher quality broadcasting including
stereo sound. In this process, instead of the amplitude of the RF carrier, it is
the frequency of the waves that changes to match that of the signal. This is
called frequency modulation.
Try the next activity to learn about the production, transmission and
reception of radio waves.
Activity 3
Sound check…
Adapted from: Littell, McDougal Science. Integrated Course 1, Teacher’s edition. McDougal
Littell, a division of Houghton Mifflin Company C79.
Objectives:
• Produce radio waves.
• Detect radio waves.
Materials:
• Two - 25 cm copper wire
• C or D battery
• electrical tape
• metal fork
• portable radio
Procedure:
1. Tape one end of the first wire to
one end of the battery. Tape one end of the second wire to the other
end of the battery.
2. Wrap the loose end of one of the wires tightly around the handle of
the fork.
3. Turn on the radio to the AM band and move the selector past all
stations until you reach static.

153
4. Hold the fork close to the radio. Stroke the free end of wire across
the fork’s prongs.
5. At a distance of 15 cm from the radio stroke again the free end of the
wire across the forks’ prongs.
6. Repeat step 5 at a distance 20 cm from the radio.
Guide Questions:
Q5. What happens when you stroke the prongs with the wire?
Q6. How does changing the position affect the results?
Q7. What might be the cause when you sometimes hear static sound in
your radio? What can be done to resolve it?
Activity 4
Then there was sound…
Adapted from: APEX Physics LP Chapter 3 Lesson 4: Student Activity 5: The Generation,
Transmission, and Reception of Radio Waves
Objectives:
• Describe how radio waves are generated, transmitted, and received.
• Name the parts of the radio transmitter and receiver and give the
functions of each part.
Materials:
• 2 sheets of Manila paper
• sticky tape or paste
• 2 envelopes containing a word or phrase written in color-coded
pieces of paper:
light blue parts of the transmitter/receiver
pink waves
white linkages
Procedure:
1. Open the envelope labeled transmitter. Arrange the strips of paper in the
order at which carrier waves are produced and then transmitted.
Blue Strips
Oscillator, microphone, modulator, amplifier, broadcast antenna,
receiver antenna

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Pink Strips
Sound waves, carrier, audio, amplified modulated carrier wave,
modulated radio
White strips
Are fed to the (2 pieces); Generates (2 pieces); Are picked up by; Are
sent to the; Increase the energy of the carrier waves and become;
Transform sound waves to electrical signal then to; Put out the
modulated carrier waves and pass them to the…
2. Once you are already sure of the arrangement, paste the strips on the
Manila paper, leaving gaps between them.
3. Draw arrows between strips of paper to show the route of the sound and
carrier waves in the transmitter. Then choose the correct linkages.
4. Open the envelope labeled receiver and arrange the strips of paper
on the other Manila paper according to how the transmitted waves are
received.
5. Follow the same procedure as in steps 2 and 3.
Blue strips
tuner; receiver antenna; amplifier; demodulation; loudspeaker
Pink strips
frequency of the weak modulated carrier waves; sound signals and
carrier waves; sound; sound
White strips
Passes the (3 pieces); Then to; Selects the; Converts sound signal
to; Removes the carrier waves leaving only the; Increases the energy
of.
6. Show the continuous transmission of waves through directional arrows.
7. Post your finished work on the board and explain.
Guide Questions:
Q8. What common problems could arise during transmission and
reception of radio waves? Explain the possible cause/s of those
problems.

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Microwaves
Microwaves have smaller wavelengths than radio waves. They are used
in satellite communications, radar, television transmission and cooking.
Applications of Microwaves
Satellite Communications
Microwaves can penetrate the atmosphere of the earth. This is the
reason why they are used for satellite communications. Communication
satellites travel around the earth at an altitude of 35, 000 km above the equator.
They move at a speed of 11 300 km/h and revolve around the earth every 24
hours, the same rate as the rotation of the earth. This makes them appear
to be stationary when seen on Earth. Antennae are mounted to point in fixed
directions towards these satellites. Microwaves signals are transmitted by an
antenna to a satellite which amplifies and re-transmits the signal to an antenna
in other parts of the world. This is how we communicate with the rest of the
world.
http://www.esa.int/Our_Activities/Navigation/Galileo_satellite_set_for_new_orbit
Figure 4. An orbiting satellite
Radar
http://phys.org/news/2013-03-nasa-kaboom-experimental-asteroid-radar.html
Figure 5. A radar

156
Microwaves have short wavelengths and are reflected by small objects.
This property is used in radars. Radar is the acronym of radio detection and
ranging. A radar system is consists of an antenna, transmitter, and a receiver.
The antenna whirls around continuously to scan the surrounding area. The
transmitter sends out a narrow beam of microwaves in short pulses. A distant
object reflects some of the signal back to the receiver. The direction to which
the signal was received gives the direction of the object. The distance of the
object can be calculated from the time lag between the transmitted pulse and
the reflected pulse.
Terrestrial Communication
Microwaves are used to transmit
television news coverage from mobile
broadcast vehicles back to the station. The
news crew can also set up a small antenna
to send signals to a communication satellite.
This is how news are broadcasted and
watched live around the world.
Figure 6. A Television set
A cell phone is a radio transmitter and receiver that uses microwaves.
Cellular phones depend on overlapping network of cells or areas of land
several kilometres in diameter. Each cell has its tower that receives and sends
microwave signals. The figure below will give you further understanding on the
process.
Figure 7. Transmission and reception of signals by a cellular phone

157
Microwave oven
In a microwave oven, foods absorb certain microwave frequencies very
strongly. The microwaves penetrate the food being heated. It will agitate the
water molecules within the food, thus creating molecular friction which then
produces heat that will cook it.
http://linmabeltech.com/?attachment_id=885
Figure 8. A microwave oven
The next activity will give you an idea about the next type of EM wave, the
infrared wave.
Activity 5
It’s getting hotter
Objectives:
• Discover infrared and its effect.
• Explain the relationship between frequency and the energy carried
by an EM wave.
Materials:
• prism
• 3 alcohol thermometers with blackened bulb
• sunlight
Procedure:
1. This experiment must be done in sunlight.
2. Take the initial readings of the three thermometerse while in the
shade. Record your readings in a data table similar to the table below.
3. Let the sunlight pass through the prism to split the sun’s white light
into its component colors.
4. Position one thermometer in the blue region.
5. Position another thermometer in the yellow region.
6. Position the last thermometer just below the red region.

158
7. Measure the temperature every after 2 minutes for 10 minutes.
8. Record the temperature readings in the three regions in the table
below.
Time
Temperature Readings
1st Thermometer
(Blue Region)
2nd Thermometer
(Yellow Region)
3rd Thermometer
(Red Region)
0
2 minutes
4 minutes
6 minutes
8 minutes
10 minutes
Guide Questions:
Q9. Did you see any trend? Explain if there is any.
Q10. What did you notice about the temperature readings?
Q11. In which region have you recorded the highest temperature after
10 minutes?
Q12. What do you think exists just beyond the red part of the spectrum?
Q13. Discuss any other observations or problems.
Infrared
Infrared radiation lies beyond the red end of the visible light. It is emitted
by all objects. The amount and wavelength of radiation depend on temperature.
Below 500oC, an object emits only infrared radiation. Above 500oC, an object
glows and emits both infrared and some visible light.
Our bodies radiate infrared and under infrared camera or a night vision
goggle, our images appear in variety of colors.The differences in color determine
the differences in temperature. For example, shades of blue and green indicate
regions of colder temperature; and red and yellow indicate warmer temperature.

159
Figure 9. Infrared image of a dog
In Figure 9, the dog is covered with thick coat of fur that prevents the
heat generated by the dog’s body from escaping. Notice that the dog’s nose is
cold while the eyes and mouth areas are warm.
The following are some useful applications of IR radiation:
1. Infrared photographs taken from a satellite with special films provide
useful details of the vegetation on the Earth’s surface.
2. Infrared scanners are used to show the temperature variation of the
body. This can be used for medical diagnosis.
3. Infrared remote controls are used in TVs, video, cassette recorders,
and other electronic appliances.
4. Some night-vision goggles use IR.
5. Some autofocus cameras have transmitter that sends out infrared
pulses. The pulses are reflected by the object to be photographed
back to the camera. The distance of the object is calculated by the
time lag between the sending and receiving of pulses. The lens is
then driven by a built-in motor to adjust to get the correct focus of the
object.

160
The Visible Spectrum

Whenwhitelightpassesthroughaprism,itisseparatedintoitsconstituent
colors: the red, orange, yellow, green, blue, indigo and violet. These colors do
not distinctly separate but they continuously change from red to violet. Red
color has the longest wavelength from among these colors and violet has the
shortest.
Figure 10. The Visible Spectrum
Our eyes are sensitive to electromagnetic waves of wavelengths that
ranges from 4x10-7
m to 7x10-7
m. This is the range of wavelengths of white
light. Thus, the spectrum of white light is therefore called the visible spectrum.
Table 3 shows the wavelengths of the different colors that constitute the white
light.
Table 3. The Wavelength of the Different Colors of Light
Color Wavelength (nm)
Violet - Indigo 390 to 455
Blue 455 to 492
Green 492 to 577
Yellow 577 to 597
Orange 597 to 622
Red 622 to 700
The next activity introduces the next part of the electromagnetic
spectrum. Perform this activity to have a deeper understanding about this kind
of EM wave. This activity should be done early in the morning so as to expose
the material throughout the day.

161
Activity 6
Screen the UV out
Objectives:
• Block UV rays of the sun.
• Discover the effects of UV rays.
Materials:
• Ziploc snack bag
• newspaper
• sunscreen/sunblock
• black construction paper
• permanent marker
Procedure:
1. Cut a piece of newspaper to fit snugly inside a Ziploc snack bag.
2. Outside the snack bag, draw two lines with a marker dividing the bag
into three equal parts from the top of the bag to the bottom.
3. Apply a thin coat of sunscreen in the leftmost part.
4. Cover the middle part with black construction paper.
5. The right part should be left fully exposed.
6. Place the snack bags in a place fully exposed to sunlight.
7. Recover the snack bags in the afternoon.
Guide Questions:
Q14.Howdoesthenewsprintvaryinthethreedivisionsofthenewspaper?
Q15. What does this indicate?
Q16. How does this realization impact to your personal life?
Extension Activity: For a more noticeable result, continue exposing the material
for several days.
Perform the same activity during a cloudy day or inside the house.
Observe and compare the degree of effect to that during a bright sunny day.
Ultraviolet Radiation
Ultraviolet radiation lies just beyond the violet end of the visible spectrum.
Ultraviolet waves have shorter wavelengths than the visible light and carry more
energy.

162
Some Uses of UV Radiation
The sun is our main source of ultraviolet radiation but there are also
artificial sources of UV light. Ultraviolet radiation in UV lamps are used by
banks to check the signature on a passbook. The signature is marked on
the passbook with fluorescent ink. It becomes visible when viewed under an
ultraviolet lamp. These lamps are also used to identify fake banknotes.
Ultraviolet radiation is also used in sterilizing water from drinking
fountains. Some washing powder also contains fluorescent chemicals which
glow in sunlight. This makes your shirt look whiter than white in daylight.
Ultraviolet radiation in sunlight produces vitamin D in the skin and gives
us tanning effect. But since UV rays have high energy, it could be harmful to
some extent. It could burn the skin and hurt our eyes. Overexposure to UV
radiation may cause skin cancer. Suntan or sunscreen lotions serve as filters
to protect the body from ultraviolet radiation.
X-rays
X-rays come just after the ultraviolet rays. They are of shorter wavelength
but carries higher energy than the UV.
X-rays are produced using an X-ray
tube. They are emitted when fast moving
electrons hit a metal target. X-rays were
discovered by Wilhelm Conrad Roentgen
in 1895.

LongwavelengthX-rayscanpenetrate
the flesh but not the bones. They are used
in X-ray photography to help doctors
look inside the body. They are useful in
diagnosing bone fractures and tumors.
Figure 11. An X-ray film
Short wavelength X-rays can penetrate even through metals. They are
used in industry to inspect welded joints for faults.
All X-rays are dangerous because they can damage healthy living cells
of the body. This is the reason why frequent exposure to X-rays should be
avoided. Too much exposure to X-rays can damage body tissues and can
cause cancer.

163
Gamma Rays
Gamma rays lie at the other end of the electromagnetic spectrum. They
are shortest in wavelength and highest in frequency. They carry the highest
amount of energy, thus, they are more dangerous. Gamma rays are emitted
by stars and some radioactive substances. They can only be blocked with lead
and thick concrete.
Gamma rays are very strong that they can kill living cells. Gamma rays
are used to treat cancer through the process called radiotherapy. They are also
used for sterilization of drinking water.
• A wave is a disturbance that transfers energy.
• James Clerk Maxwell formulated the Electromagnetic Wave Theory
which says that an oscillating electric current should be capable of
radiating energy in the form of electromagnetic waves.
• Heinrich Hertz discovered the Hertzian waves which is now known as
radio waves.
• Hertz is the unit used to measure the frequency of waves.
• Electromagnetic (EM) waves have unique properties.
►► EM waves can travel through a vacuum.
►► EM waves travel at the speed which is constant in a given medium
and has a value of c = 3.0 x 108 m/s in vacuum.
►► EM waves are disturbances in a field rather than in a medium.
►► EM waves have an electric field that travels perpendicular with
the magnetic field.
►► EM waves form when moving charged particles transfer energy
through a field.
• Most EM waves are invisible to the eye but detectable. Only the visible
light is seen by humans.
• Waves in the EM spectrum include the following from the longest
wavelength to the shortest wavelength.
►► Radio waves
►► Microwaves
►► Infrared waves
►► Visible light
►► Ultraviolet
►► X-rays
►► Gamma rays
The order also shows the increasing frequency and energy of the EM
waves.

164
• The waves in the various regions in the EM spectrum share similar
properties but differ in wavelength, frequency, energy, and method of
production.
• The regions in the EM spectrum have various uses and applications as
follows:
EM Wave Applications / Uses
Radio waves Radio and television communication
Microwaves Satellitetelevisionandcommunication
Infrared waves Remote control, household electrical
appliances
Visible light Artificial lighting, optical fibers in
medical uses, screen of electronic
devices
Ultraviolet Sterilization, Fluorescence
X-rays Medical use, engineering applications
Gamma rays Medical treatment
• Each type of EM wave poses a certain degree of risk and danger to
people and environment.

165
A. Multiple Choice. Choose the letter of the correct answer.
1. Which electromagnetic wave carries more energy than the others?
a. microwaves
b. radio waves
c. UV radiation
d. visible light
2. What electromagnetic wave is sometimes called heat rays?
a. gamma rays
b. infrared
c. radio waves
d. visible light
3. What is the frequency range of UV radiation?
a. 3.5 x 109
-3 x 1011
Hz
b. 3.5 x 1011
- 3 x 10114
Hz
c. 7.5 x 1014
- 3 x 1016
Hz
d. 7.5 x 1016
- 3 x 1019
Hz
4. What is the range of frequencies are our eyes sensitive to?
a. 3 x 109
- 3 x 1011
Hz
b. 3 x 1011
- 4 x 1014
Hz
c. 4 x 1014
- 7.5 x 1014
Hz
d. 7.5 x 1014
- 3 x 1016
Hz
5. What is the wavelength of the wave with a frequency of 3 x 109 Hz?
a. 1.0 x 10-1
m
b. 1.0 x 101
m
c. 1.0 x 10-2
m
d. 1.0 x 102
m
B. Below are the applications of electromagnetic waves. State the type of
electromagnetic wave used in each application.
1. Satellite communications
2. Texting
3. TV broadcasting
4. Radar
5. Checking bankbook signature

166
C. Answer the following questions briefly.
1. Describe the mathematical relationship between frequency and
wavelength.
2. What is the function of a tower in cell phone operation?
3. What does a radio transmitter do?
4. How can infrared radiation be detected if cannot be seen?
5. Why are high frequency electromagnetic waves like gamma rays harmful
to living things?
Glossary of Terms
Electromagnetic wave a disturbance in a field that carries energy and
does not require a medium to travel
Frequency number of cycles a wave completes in one
second; expressed in Hertz
Radar short for radio detecting and ranging. A way of
detecting aircrafts and ships from a distance
and estimating their locations
Radio Receivers receives radio waves and convert them back to
sounds
Radio Transmitter attaches information to the radio signal by
modulating it
Wavelength the distance measured from one crest of a
wave to the next crest or from one through to
the second through

167
Printed Materials:
Glencoe Physics Principles & Problems. The McGraw-Hill Companies, Inc.,
2013
Kirkpatrick et. al. Physics: A World View, International Student Edition. The
Tomson Corporation, 2007.
Littell, McDougal. Science, Integrated Course 1, Teacher’s Edition. Evanston,
Illinois: McDougal Littell, 2005.
Padua, AL., Crisostomo RM., Practical and Explorational Physics Modular
Approach. Vibal Publshing House, Inc., Copyright 2003
Yong, et al. Physics Insights, Low Price Edition. Jurong, Singapore: Pearson
Education (Asia) Pte Ltd.
Electronic Sources:
http://www.imaginationstationtoledo.org
http://www.can-do.com/uci/ssi2001/emspectrum.html
http://www.physicsclassroom.com/mmedia/waves/em.cfm
http://science.hq.nasa.gov/kids/imagers/ems/ems2.html
http://www.scienceinschool.org/2009/issue12/microwaves
http://enviroadvocacy.com/measure-your-campaign/
http://sciencevault.net/11hscphys/82worldcommunicates/823%20em%20
waves.htm
http://www.colorado.edu/
http://school.discoveryeducation.com/lessonplans/interact/
electromagneticspectrum.html
http://www.sciencebuddies.org/
http://webs.mn.catholic.edu.au/science/wilko/is94/notes/no2.htm
http://www.esa.int/Our_Activities/Navigation/Galileo_satellite_set_for_new_
orbit
http://phys.org/news/2013-03-nasa-kaboom-experimental-asteroid-radar.html
http://linmabeltech.com/?attachment_id=885

168
I. Introduction
In the previous module, you learned about electromagnetic spectrum.
You gained an understanding of the different electromagnetic waves and their
benefits. One of the most common among these electromagnetic waves is the
visible light.
In this module, you will study two of the properties of visible light -
reflection and refraction. Acloser look into these properties will be done through
different observable examples and experimentations using mirrors and lenses.
As you walk through the pages of this module, you will be able to use the
laws of reflection and refraction in order to describe and explain how images
are formed by mirrors and lenses. You will also be able to solve problems
pertaining to the position and magnification of images formed by mirrors and
lenses.
One of the thrusts of this module is to make you aware of the purposes
of the different types of mirrors and lenses so you can select the right type of
mirrors and lenses that you can use in your daily lives.
At the end of Module 3, you will be able to answer the following questions:
LIGHT: MIRRORS &
LENSES
1. How do the laws of reflection and refraction explain the functions
of some optical instruments?
2. How does changing the location of the object from the lens/mirror
affect the image formed?
3. How does changing the focal length of the lens/curved mirror affect
the image formed?
Unit 2
MODULE
3

169
1. Predict the qualitative characteristics (location, orientation, type, and
magnification) of images formed by plane and curved mirrors and
lenses.
2. Determine the quantitative characteristics (location, orientation, type,
and magnification) of images formed by plane and curved mirrors.
and lenses.
3. Distinguish between converging and diverging mirrors and lenses.
4. Apply ray diagramming techniques in describing the characteristics
and positions of images formed by mirrors and lenses.
5. Derive the mirror and lens equations.
6. Identify ways in which the properties of mirrors and lenses determine
their use in optical instruments (e.g., cameras and telescopes).
III. Pre-Assessment
Directions. Choose the letter of the correct answer.
1. You see the reflection of the clock without numbers in your plane mirror. The
image formed by the hands of the clock shows the time of 3:30. What is the
real time?
a. 3:30
b. 8:30
c. 9:30
d. 10:30
2. How much larger will your classroom seem to appear if the entire two adja-
cent walls of your classroom consist of plane mirrors?
a. 2x larger
b. 3x larger
c. 4x larger
d. can’t be determined
3. Where is the image located if an object is 30 cm in front of convex mirror
with a focal length of 20 cm?
a. Between F and V
b. Between C and F
c. In front of the mirror
d. Can’t be determined

170
4. What is the distance of your image from you if you stand 1.5m in front of a
plane mirror?
a. 1.5 m
b. 2.0 m
c. 3.0 m
d. 4.5 m
5. Zed stands 1.5-m tall in front of a plane mirror. What is the height of his
image?
a. 4.5 m
b. 3.0 m
c. 2.0 m
d. 1.5 m
6. A light ray, traveling parallel to a concave mirror’s axis, strikes the mirror’s
surface. The reflected ray __________.
a. passes through the mirror’s focal point
b. again travels parallel to the mirror’s axis
c. travels at right angles to the mirror’s axis
d. passes through the mirror’s center of curvature
7. An object is placed between a concave mirror and its focal point. What is
the type and orientation of the image formed?
a. virtual and inverted
b. real and inverted
c. virtual and erect
d. real and erect
8. What kind of mirror is used in automobiles and trucks to give the driver a
wider area and smaller image of traffic behind him?
a. Plane mirror
b. Convex mirror
c. Concave mirror
9. What type of mirror do dentists usually use to see clearly the images of our
teeth?
a. Plane mirror
b. Convex mirror
c. Concave mirror

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10. When a small object is placed on the principal axis of a concave mirror
between the focus and the mirror (as in the figure below), the image formed
is ____________.
a. erect, magnified, and virtual
b. inverted, magnified, and real
c. inverted, reduced, and real
d. erect, reduced, and real
11. A white sheet of paper cannot act as mirror because it ____________ the
rays of light.
a. diffracts
b. diffuses
c. interferes
d. refract
12. You see your face clearly if you look down on a pool of still water. Which one
of the following statements gives the best explanation for this observation?
a. Light entering the water is dispersed.
b. Regular reflection of light happens on the surface of still water.
c. Irregular reflection of light happens on the surface of still water.
d. Light is reflected from the surface of water in different directions.
13. Where should the object be placed in front of a concave mirror to form a
virtual and magnified image?
a. At the focus
b. At the center of curvature
c. Between the focus and the vertex
d. Between the center of curvature and focus
14. Which of the following is/are true of a concave mirror?
I. It will never form a real image
II. An inverted image will be formed if the object distance is
greater than the focal length
III. An object can be magnified if placed at f
a. I only
b. II only
c. I and II
d. I, II, and III

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15. A light ray, traveling parallel to a concave lens’ axis and strikes the lens, will
refract and__________.
a. pass through the lens’ focal point
b. travel parallel to the principal axis
c. continue to travel in the same direction
d. travel at right angles to the principal axis
16. What kind of image is formed by concave lenses?
a. always real
b. always virtual
c. could be real or virtual; depends on the distance of the object from the
focal point
d. could be real or virtual, but always real when the object is placed at the
focal point
17. Sun’s rays are observed to focus at a point behind a lens. What kind of lens
was used?
a. Converging Lens
b. Diverging Lens
c. Focusing Lens
18. This optical instrument uses 2 convex lenses to make a smaller object larger.
a. Camera
b. Microscope
c. Oscilloscope
d. Telescope
19. Which of the following optical instruments will be used to produce a reduced
and inverted image of a distant object?
a. Camera
b. Projector
c. Microscope
d. Refracting Telescope
20. A photocopy “Xerox” machine produces an image that is of equal size as
the object. Considering the location of an object in a convex lens, where is
the object located or placed to produce an image that is of equal size to the
object?
a. At F’
b. At 2F’
c. Between F’ and V
d. Between 2F’ and F’

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Reflection of Light in Mirrors
Have you noticed the word “AMBULANCE” in an ambulance car? How
is it written? Did you ever wonder why it is written that way? You will find the
answers to these questions as you go through this module. Try the following
activity to study one of the properties of light.
Activity 1
Mirror, mirror, on the wall…
Objectives:
• Determine the height, width, and the distance from the mirror of the
image formed by plane mirrors.
• Compare the actual height, width and the distance from the mirror of
the object with that of the image formed by plane mirror.
Materials:
• 1 (10 cm x 15 cm) plane mirror
• 1 graphing paper
• 10 one–peso coins
• modeling clay
• pen
Procedure:
1. Let the mirror stand vertically along a line on a graphing paper as shown in
Figure 1. Use the modeling clay to support the plane mirror.
Figure 1. A Plane Mirror on a Graphing Paper.
2. Using a pen, make three (3) different marks along the intersections on the
graphing paper in front of a mirror.
Modeling clay
Mirror

174
3. Measure the distance of each mark from the mirror by counting the number
of parallel lines between the mark and the base of the plane mirror. Record
your data in a table similar to Table 1 below.
4. Look at the images of the marks formed by the mirror. Measure the distance
of each image from the mirror by counting the number of parallel lines
between the image and the base of the mirror. Record this also in Table 1.
Table 1. Distance of the Object and Image from the Mirror
Mark
Number of Parallel Lines
Between the Mark
and the Mirror
Between the Image
and the Mirror
Mark 1
Mark 2
Mark 3
Q1. Refer to Table 1, compare the distance (number of parallel lines) from
the mirror of the object with that of the image.
5. Stack 10 pieces of one-peso coin in front of the plane mirror as in Figure 2.
Using a ruler, measure the height and width of the stack of coins. Measure
also the height and width of the image as seen on the mirror. Enter your
measurements in a table similar to Table 2.
Figure 2. Stack of Coins In front of the Plane Mirror
Table 2. Height and Width of Object and Image
Description Object Image
Height (cm)
Width (cm)
Q2. How do the height and width of the object compare with the height and
width of the image?

175
Reflection is the bouncing off of light rays when it hits a surface like a
plane mirror. In the activity, you used plane mirrors and located the object
distance, p and the image distance, q and found out that p is equal to q. In
plane mirrors, the image appears as if it is behind the mirror but actually not,
so the image is virtual. The value therefore of image distance, q is negative.
The height of the image, h’ in plane mirrors is always the same as the height
of the object, thus its magnification, M is 1. The magnification formula is written
below:
To learn more about reflection of light in plane mirrors, try the next activity.
However, here are some important terms which you need to understand first.
Incident Ray. The ray of light approaching the mirror represented by an
arrow approaching an optical element like mirrors.
Reflected Ray. The ray of light which
leaves the mirror and is represented by an
arrow pointing away from the mirror.
Normal Line. An imaginary line
(labeled N in Figure 3) that can be drawn
perpendicular to the surface of the mirror
at the point of incidence where the ray
strikes the mirror.
The angle between the incident ray and the normal line is known as the
angle of incidence, Өi
. The angle between the reflected ray and the normal is
known as the angle of reflection, Өr
.
Figure 3. Reflection of a
Light Ray on a Plane Mirror

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Activity 2
Angle of Incidence vs. Angle of Reflection
Objectives:
• Compare the angle of reflection and the angle of incidence.
• State one of the laws of reflection.
Materials:
• 1 plane mirror
• 1 low – frequency laser/ laser pen/laser pointer
• 1 paper protractor (see Appendix A)
Procedure:
1. Let the mirror stand vertically along the edge of the paper protractor as
shown in Figure 4. Use the clay to support the plane mirror.
Figure 4. A Plane mirror on a paper protractor
2. Position the laser beam such that it hits the mirror at an angle of 10o
with the
normal line. Measure the angle between the reflected ray and the normal
line. Record your measurement in a table similar to Table 3.
3. Make three trials and get the average.
4. Repeat steps 2 to 4 for angles 20o
, 30o
, 40o
, and 50o
. Enter all your
measurements in Table 3.
Table 3. Angles of Incidence and Reflection
Angle of Incidence
Angle of Reflection
Trial 1 Trial 2 Trial 3 Ave.
10o
20o
30o
40o
50o

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Q3. How does the angle of incidence compare with the angle of
reflection?
Q4. A periscope is an instrument for observation over, around or through
an obstacle. Explain how light travels in a periscope. Diagram the
light rays as these pass through the periscope.
In the activity, you found out that the angle of incidence (Өi
) is equal to
the angle of reflection (Өr
).
In symbols:
Өi
= Өr
This is one of the laws of reflection. The other law states that:
“The normal line, incident ray, and the reflected ray lie on the same
plane.”
Reflection of light is employed significantly in making optical instruments like
periscopes. Periscopes allow sea navigators in a submarine to see the surface of the
water.
Try the next activity to further investigate the reflection of light in plane mirrors
Activity 3
Mirror Left-Right Reversal
Objectives:
• Describe the images formed by plane mirror.
• Show an understanding of reversal effect in mirrors by writing laterally
inverted letters and words.
Materials:
• alphabet chart
• 1 plane mirror
Procedure:
1. Place the alphabet chart in front of the plane mirror. Identify all capital
letters in the alphabet that can be read properly in front of the mirror.
2. Write at least 3 words (all in capital letters) that can be read properly both
with a mirror and without a mirror in front of it.

178
Q5. What are the letters of the alphabet (in capital) that can be read
properly in front of a mirror?
Q6. Think of words (in capital letters) that can be read properly both with
a mirror and without a mirror. What are these words?
Q7. Write the sentence below on a clear sheet of paper in such a way
that it can be read properly in front of a mirror:
Honesty is the best policy.
Mirror Left-Right Reversal
Figure 5 shows a girl combing her hair with
her left hand. However, in her image, you will notice
that she is combing her hair with her right hand. This
effect is known as the mirror left-right reversal. The
left side of the object appears as the right side of the
image and the right side appears as the left. This
also explains why the word “AMBULANCE” in an am-
bulance car is flipped.
Do the next activity to learn more about reflection of light, this time using
two plane mirrors. You will explore how the angle between two plane mirrors
affects the number of images formed.
Activity 4
Who wants to be a Millionaire?
Objectives:
• Identify the relationship between the number of images formed and
the angle between the two mirrors.
• Use the gathered data to derive the formula for determining the
number of images formed when two mirrors are kept at a certain
angle.
Materials:
• 1 one-peso coin
• 1 paper protractor
• 2 plane mirrors
Figure 5. Mirror Left-Right
Reversal

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Procedure:
1. Place two plane mirrors at an angle of 90o
and place the one-peso coin
between the mirrors as shown in Figure 6.
Figure 6. Two plane mirrors at 90 degree angle
2. Count the number of images formed. Record this in a table similar to Table
4 below.
3. Try to vary the angle between the mirrors.
Q8. What happens to the number of images formed as you vary the
angle between the mirrors?
4. Set the angle between the mirrors to 60o
. Count and record again the
number of images formed.
5. Do again step 4 for angles 45o
and 30o
. Enter all the values in a table similar
to Table 4
Table 4. Number of Images Formed
Angle Number of Images
90o
60o
45o
30o
Q9. Refer to Table 4. What relationship exists between the number of
images formed and the angle between two mirrors?
Q10. Use the data in Table 4 to derive the formula for determining the
number of images formed by two mirrors?
Q11. How should the mirrors be arranged such that an infinite number
of images will be formed or seen?

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Multiple Images
Have you seen a lot of money in your
previous activity? Multiple images are formed by
the reflection that happens when arranging at
least two mirrors. Figure 7 shows three images
of a toy car in front of two mirrors at 90o
. The
number of images, N, can be determined using
the formula N = (360/angle between the mirror)
-1. Parallel mirrors on the other hand produce
infinite number of images.
Reflection not only happens on a smooth surface like plane mirrors, but
also happens on rough surfaces. This is why reflection is classified into two
types.
Types of Reflection:
1. Specular/ Regular Reflection. This is a reflection of light on smooth surfaces
such as mirrors or a calm body of water. An example of this is the image of
the Mayon volcano on a calm water shown in Figure 8b.
(a) (b)
Sources: http://www.orcagrowfilm.com/Articles.asp?ID=148 & http://www.wallpaperup.
com/225284/landscape_nature_trees_mountain_Mount_Mayon_Philippines_Luzon_
reflection_volcano_g.html
Figure 8. Specular Reflection. (a) Parallel light rays reflect in one direction (b) Mayon
Volcano and its reflection on calm water
2. Diffused/Irregular Reflection. This is a reflection of light on rough surfaces
such as clothing, paper, wavy water, and the asphalt roadway. An example
of this is the image of a mountain on a wavy body of water as shown in
Figure 9b.
Figure 7. Multiple Images Formed by
Two Plane Mirrors at 90o
Angle

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(a) (b)
Sources: http://www.orcagrowfilm.com/Articles.asp?ID=148 & http://www.wallpaperup.
com/29790/sunset_mountains_reflection.html
Figure 9. Diffused Reflection. (a) Parallel light rays reflect in different directions. (b) A
mountain and its reflection on wavy water
The following lesson presents a specular/ regular reflection (because it
happens on a smooth surface) but the reflected rays do not follow one direction.
Why is that so? Let us find out.
Reflection on Spherical Mirrors
Look at your reflection on a shiny metal spoon. Is your reflection the
same on the two surfaces of the spoon? How will you compare your reflection
on the two surfaces of the spoon? This is a reflection on curved mirrors.
A curved mirror is a reflecting surface in which its surface is a section
of sphere. There are two kinds of curved mirrors, the concave and the convex
mirrors. A spoon is a kind of a curved mirror with both concave and convex
surfaces.
Two Kinds of Spherical Mirrors:
1. The Concave Mirror
• It is a curved mirror in
which the reflective surface
bulges away from the light
source.
• It is called Converging
Mirror because the parallel
incident rays converge or
meet/intersect at a focal
point after reflection.
Figure 10. Parallel rays converge after reflection
on a concave mirror

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2. The Convex Mirror
• It is a curved mirror
in which the reflective
surface bulges towards the
light source.
• It is called Diverging Mirror
because the parallel
incident rays diverge
after reflection. When
extending the reflected
rays behind the mirror, the
rays converge at the focus
behind the mirror.
To know more about curved mirrors and how images are formed when
objects are placed in front of them, try Activity 5 below.
Activity 5
Images Formed by Curved Mirrors
Objective:
Describe the location, size, and orientation of the images formed by
curved mirrors.
Materials:
• Improvised optical bench apparatus
• Curved mirror (concave and convex)
• Mirror stand
• Screen or white cardboard
• Flashlight
• Meter stick
• Sheet of paper (colored black)
Procedure:
1. Cut a U-shaped object from a cartolina with a size that fits the glass cover
of the flashlight. Attach the U-shaped object to the cover of the flashlight.
Refer to Figure 12.

Figure 11. Parallel light rays diverge after reflection
on a convex mirror

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2. Position the concave mirror intact with the mirror stand at the center of two
meter sticks as shown in Figure 13 below.
3. Mark the improvised optical bench or meter sticks at the following points:
the focal point F (see the specified focal length on label of the mirror), and
the center of curvature, C which is equal to 2F.
4. Place the flashlight at a distance farther than the center of curvature, C in
front of the mirror.
5. Allow the light rays coming from the flashlight to strike the mirror.
6. Place a screen (a white cardboard) at a distance in front of the mirror. Move
the screen in different distances in front of the mirror until a clear and sharp
image of the U-shape is formed on the screen. Note the size and location of
the image formed (on the screen).
7. Do the same thing in different location of the object by moving the flashlight
at the center of curvature C, near the focal point, F at the focal point, and
between the focal point and the mirror.
Figure 12. A U-shaped object attached to the flashlight
Figure 13. Set-up for Curved Mirror Experiment

184
Q12. What happens to the size and location of the image when you
bring the flashlight nearer to the concave mirror?
8. Repeat steps 3, 5, and 7 using a convex mirror. This time, you will not use
the screen. Look through the convex mirror to see the image.
Q13. What is the generalization from the nature of images formed by
convex mirror and concave mirror?
This activity is adapted from Lesson Plans in Science IV, Unit II Energy in the Environment,
Activity 2.5 Images Formed by Curved Mirrors.

In Activity 5 using a concave mirror, you observed that images formed on
the screen are inverted. Images formed on a screen, after reflection, are called
real images because they are formed by the intersection of real reflected rays.
A virtual image, on the other hand, does not form on a screen because
a virtual image is formed by the intersection of non-real rays.
Images Formed by Curved Mirrors
In locating the image formed in curved mirror graphically, three important
points are considered. The following important points are enumerated below.
(a)
Figure 14. Curved Mirrors (a) Concave Mirror (b) Convex Mirror
(b)
• Center of Curvature, C -
the center of the sphere of
which the mirror is part. Its
distance from the mirror is
known as the radius.
• Vertex, V - the center of the
mirror.
• Focal Point/ Focus, F - the
point between the center of
the curvature and vertex. Its
distance from the mirror is
known as the focal length, f.
Principal axis
Principal axis

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The ‘Four Principal Rays’ in Curved Mirrors
Images formed in a curved mirror can be located and described through
ray diagramming. The P – F ray, F – P ray, C – C ray, and the V ray are the
‘Four Principal Rays’ in curve mirrors. These rays, applied for concave and
convex mirrors, are presented in Table 5.
Table 5. The ‘Four Principal Rays’ on Concave and Convex Mirrors
Concave Mirror (Converging
Mirror)
Convex Mirror (Diverging Mirror)
1. P – F Ray. A ray of light parallel
to the principal axis is reflected
passing through the principal
focus, F.
1. P – F Ray. A ray of light parallel
to the principal axis is reflected
as if passing through the principal
focus, F.
2. F – P Ray. A ray of light passing
through the focus, F is reflected
parallel to the principal axis.
2. F – P Ray. A ray of light directed
towards the focus, F is reflected
parallel to the principal axis.
actual
reflected ray
imaginary
extension of the
reflected ray
imaginary
extension of the
reflected ray
actual
reflected
ray

186
3. C – C Ray. A ray of light passing
through the center of curvature, C
reflects back along its own path.
3. C – C Ray. A ray of light directed
towards the center of curvature, C
reflects back along its own path.
4. V Ray. A ray of light directed to
the vertex reflects at equal angle
from the principal axis
4. V Ray. A ray of light directed to
the vertex reflects at equal angle
from the principal axis.
In determining the position and nature of the image graphically, the ‘Four
Principal Rays’ are used. Ray diagramming is used in the graphical method of
locating the image. The following are ray diagramming steps using the ‘Four
Principal Rays’ in determining the position and the nature of the image of an
object formed by concave mirror and convex mirror.
1. From the object, draw the first ray (P – F ray). From the same point on the
object, draw the second (F – P ray), third (C – C ray), and fourth (V ray)
rays.
2. The intersection of the four rays is the image point corresponding to the
object point. For example, if you started diagramming from the tip of the
arrow-shaped object, the intersection of the reflected rays is also the tip of
the arrow-shaped image. Thus, you can determine completely the position
and characteristics of the image.
actual
reflected ray imaginary
extension of the
reflected ray
imaginary
extension of the
reflected ray
actual
reflected ray

187
3. For a convex mirror, light rays diverge after reflection and converge from a
point that seems to be behind the mirror (virtual focus); but the procedure
for locating images is the same as for concave mirror.
In the next activity, you will use the steps described above to locate
and describe the images formed by concave and convex mirrors through
graphical method. To do this, always start by drawing the curved mirror and
its principal axis, then identify the F and C on the principal axis. Next is to
draw the object then diagram the rays from the object.
Activity 6
Are you L-O-S-T after Reflection?
Objective:
Construct ray diagrams to determine the location, orientation, size,
and type of images formed by curved mirror.
Materials:
• Protractor and ruler
• Sheets of paper
Procedure:
1. Using the protractor and the ruler, copy each of the diagrams (A – G) below
on a separate sheet of paper. As much as possible, use the four principal
rays to locate the image formed in a curved mirror.
Concave Mirror
A. B.

188
C. D.
E.
Convex Mirror
F. G.

2. Use a table similar to Table 6 below to summarize the characteristics and
location of the images formed.

189
Table 6. Location, Orientation, Size, and Type of Image Formed in Curved Mirrors
Location of Object
Image
Location Orientation
(upright or
inverted)
Size (same,
reduced or
enlarged)
Type
(real or virtual)
CONCAVE
A. Farther than the
Center of Curvature
B. At the Center of
Curvature
C. Between the Center
of Curvature and the
Focal point
D. At the Focal point
E. Between the Focal
point and the Center
of the lens (Vertex)
CONVEX
F. Farther than C in
front of the Mirror
G. Between F and V in
front of the Mirror
Q14. Refer to Table 6. How does the location of the object affect the
characteristics and location of the image formed in a concave
mirror? Convex mirror?

Q15. What type of mirror do dentists usually use to clearly see the
images of our teeth? Why?
Q16. What kind of curved mirror do you see in most of the department
stores? Why do they use such kind of mirror?
This activity, which you have just performed is more detailed on the
location, orientation, size, and type of the images formed. Did this activity in
curved mirrors confirm your observations in the previous activity (Activity 5)?

190
The Mirror Equation
Ray diagrams provide useful information about the image formed, yet
fail to provide the information in a quantitative form. Ray diagrams will help you
determine the approximate location and size of the image, but it will not provide
you with the numerical information about image distance and object size. To
determine the exact location and size of the image formed in a curved mirror,
an equation is needed. The following derivation shows the mirror equation
using the Figure 15 below.
From the first and fourth rays, similar triangles are seen in the figure
below.
From the height of the object, h and the height of the image, h’ shown in
Fig. 15 (a), you can arrive at the first equation,
Similarly, as shown in Fig. 15 (b), the second equation can be derived
as
Combining Equations 1 and 2, you will get
(a) (b)
Figure 15. Similar Triangles Formed using the (a) first ray (P – F ray) and (b ) fourth ray (V ray).
Equation 1
Equation 2
Equation 3

191
Rearranging Equation 3, you will arrive at
and finally,
where: f = focal length or distance from the mirror and the focal point, F
p = distance of the object from the mirror
q = distance of the image from the mirror
The equation above, called mirror equation, applies to both concave
and convex mirrors. However, for all location of objects in front of the convex
mirror, the image always appears as if it is located behind the mirror. It is
therefore considered that the value of image distance, q is negative. In the
same manner, the focus, F in a convex mirror is located on the other side of the
mirror (behind the mirror), thus, the focal length, f is also negative.
Sample Problem:
A 5.00-cm tall light bulb is placed at a distance of 45.0 cm from a concave
mirror having a focal length of 10.5 cm. Determine the image distance and the
image size.
Given:
height of the object, h = 5.00 cm
distance of the object, p = 45.0 cm
focal point, f = 10.5 cm
Find:
distance of the image, q = ?
height of the image, h’ = ?
Mirror Equation

192
The mirror equation must be used to determine the distance of the
image, q.
To determine the image height, the magnification equation is needed.
Since three of the four quantities in the equation are known, the fourth quantity
can be calculated.
The negative value for image height indicates that the image is an
inverted image.
Try solving this…
1. What is the image distance and image height if a 7.00-cm tall object
is placed 30.0 cm from a concave mirror having a focal length of 10.0
cm?
2. A magnified, inverted image is located a distance of 30.0 cm from
a concave mirror with a focal length of 15.0 cm. What is the object
distance?

193
Sample Problem:
What is the focal length of a convex mirror that produces an image
that appears 15.0 cm behind the mirror when the object is 27.5 cm from the
mirror?
Given:
q = -15.0 cm
p = 27.5 cm
Find:
f = ?
To determine the focal length, f, the mirror equation will be used.
Substitute and solve for f.
The negative value for focal length confirms that the mirror used is a
convex mirror.
Try solving this…
3. An object is placed 33.7 cm from the convex mirror with a focal length of
10.7 cm. Determine the image distance.
4. A 7.0-cm tall light bulb is placed a distance of 37.5 cm from a convex mirror
having a focal length of -12.5 cm. Determine the image distance and the
image size.

194
Refraction of Light in Lenses
You learned in Grade 8 that Refraction is the bending of light when it
travels from one medium to another of different optical densities. The ancient
Greeks used the concept of light refraction in their living like using a lens to
focus light rays. A lens is a transparent material made of glass or plastic that
refracts light rays and focuses (or appear to focus) them at a point.
Types of Lenses
1. Convex Lens
Figure 16. Convex Lens. (a) Parallel light rays converge after refraction. (b) A converging lens
magnifying the words from a book
• It is thicker in the center than
edges.
• It forms real images and virtual
images depending on position
of the object.
• It is also called Converging
Lens because the light that
passes through it tends to
converge at a particular point
called the focal point.
The Sign Conventions for Mirror
• f is positive (+) if the mirror is a concave mirror
• f is negative (-) if the mirror is a convex mirror
• q is (+) if the image is a real image and located on
the object’s side of the mirror.
• q is (-) if the image is a virtual image and located
behind the mirror
• h’ is (+) if the image is an upright image
• h’ is (-) if the image an inverted image
(a) (b)

195
2. Concave Lens
Figure 17. Concave Lens. (a) Parallel light rays diverge after refraction. (b) A diverging lens
demagnifying the words from a book.
Activity 7
YoU can be Magnified!
Objectives:
• Measure the focal length and linear magnification of a convex lens.
• Locate the image formed by convex lens.
• Describe the image formed by a convex lens.
Materials:
• convex lens or magnifying glass
• lens holder e.g. clay
• meterstick
• index card
Procedure:
1. Hold the convex lens under a ceiling light. A projection screen (e.g. the floor
or the surface table) should be placed under the convex lens.
2. Move the convex lens up and down until a sharp image of the ceiling light is
projected on the screen.
3. Measure the distance between the lens and the projection surface using a
ruler.
Q17. What is the focal length of the convex lens?
• It is thicker at the edges and
thinner in the center.
• It forms upright and reduced
images.
• It is also called Diverging Lens
because the light that passes
through it tends to diverge at
a particular point called the
focal point.
(a) (b)

196
Q18. How would you describe the image formed if a distant object is
used?
4. Mount the convex lens on a clay. Draw a U–shaped object on an index card
and mount the index card on another clay. Initially place the index card
beside the zero (0) mark on the meter stick, and place the lens in front of
the index card as shown in Figure 18a below:
5. Look through the lens and move the lens until you can clearly see an
enlarged and upright image of the U-shaped object as shown in Fig. 18b
below.
6. Measure the distance between the convex lens and the card using a meter
stick. Record your observation on the second column of a table similar to
Table 7.
7. Measure the distance between the lens and your eye. Record your
observation on the third column of a table similar to Table 7.
8. Move again the convex lens back and forth, until you can clearly see, this
time, an enlarged and inverted image of the U-shaped object. Then, repeat
steps 6 and 7.
9. Move again the convex lens so that you can clearly see a reduced and
upside down image of the U-shaped object. Repeat steps 6 and 7.
Figure 18a. Set-up for Lens Experiment
Figure 18 b. Looking at the U-shaped Object through the Lens

197
Table 7. Distances from the Lens of Object and your Eye
Description of
Image
Distance
between the
Object and the
lens (cm)
Distance
between the
Eye and the
lens(cm)
Enlarged and upright
Enlarged and inverted
Reduced and inverted
Q19. What kind of lenses are magnifying glasses? When a magnifying
glass produces a sharp clear image, where is the object located in
relation to the lens?
Q20. Where should a magnifying glass be placed to produce an e
larged and upright image, closer to the eye or nearer to the
object? Why?
From the activity, you were able to determine the focal length of a lens.
You were also able to measure the distance of the object and the image from
the lens. These quantities are very significant in describing the image formed.
Images formed by lenses can also be real or virtual. In Activity 7, using a
convex lens, you observed that images are formed on the screen. Images
formed on a screen, after refraction, are called real images because they are
formed by the intersection of real refracted rays. A virtual image, on the other
hand, does not form on a screen because a virtual image is formed by the
intersection of non-real rays.

198
Images Formed by Lenses
In locating the image formed in lenses graphically, two important points
are considered. The following important points are enumerated below.
Figure 19. Lenses (a) Convex Lens (b) Concave Lens
The ‘Three Most Useful Rays’ in Lenses
Images formed in a lens can be located and described through ray
diagramming. The following three most useful rays for convex and concave
lenses are presented below.
Table 8. The Three ‘Most Useful Rays’ in Convex and Concave Lenses
Convex Lens (Converging Lens) Concave Lens (Diverging Lens)
1. P–F Ray. A ray of light parallel
to the principal axis is refracted
passing through the principal
focus, F behind the lens.
1. P–F Ray. A ray of light parallel
to the principal axis is refracted
as if passing through the principal
focus, F in front of the lens.
• Vertex, V – The geometric center
of the lens.
• Focal point/ Focus, F – A point
where light rays converge (or
appears to converge) when
parallel light rays pass through a
lens. Its distance from the vertex
is called the focal length.
Principal axis
Principal axis

199
2. F–P Ray. A ray of light passing
through the focus, F in front of
the lens is refracted parallel to the
principal axis.
2. F–P Ray. A ray of light directed
towards the focus, F behind the
lens is refracted parallel to the
principal axis.
3. V Ray. A ray of light passing
through the exact center of the
lens (Vertex) continue to travel in
the same direction.
3. V Ray. A ray of light passing
through the exact center of the
lens (Vertex) continue to travel in
the same direction.
To graphically determine the position and kind of the image formed, the
ray diagram can be used. Consider the following steps using the three major
rays described above:
1. From the object, draw the first ray (P–F ray). From the same point on
the object, draw the second (F–P ray), and third (V ray) rays.
2. The intersection of the rays is the image point corresponding to the
object point. For example, if you started diagramming from the tip of
the arrow-shaped object, the intersection of the refracted rays is also
the tip of the arrow-shaped image. Thus, you can determine com-
pletely the position and characteristics of the image.

200
3. For a concave lens, light rays diverge from a virtual focus; but the
procedure for locating images is the same as for convex lenses.
In the next activity, you will use the steps described above to locate
and describe the images formed by convex and concave lenses by graphical
method. To do this, always start by drawing the lens and its principal axis, then
identify the F and 2F on the principal axis. Next is to draw the object, then
diagram the rays from the object.
Activity 8
Are you L-O-S-T after Refraction?
Objectives:
• Construct ray diagrams for lenses.
• Determine graphically the location, orientation, size, and type of
image formed.
• Show graphically the changes in the image formed as an object’s
position is changed.
Materials:
• paper
• ruler
Procedure:
1. Copy each of the diagrams (A–H) below on a clear sheet of paper. Construct
ray diagram using, as much as possible, the ‘three most useful rays’ for
each of the following cases to determine the location, orientation, size, and
type of the image.

201
Convex Lens
A. B.
C. D.
E.

202
Concave Lens
F. G.
H.
2. Use a table similar to Table 9 below to summarize the characteristics and
location of the images formed.

203
Table 9. Location, Orientation, Size, and Type of Image Formed by Lenses
Location of Object
Image
Location Orientation
(upright or inverted)
Size (same,
reduced or
enlarged)
Type
(real or virtual)
CONVEX LENS
A. Beyond 2F’
B. At 2F’
C. Between 2F’ and
F’
D. At the Focal
point, F’
E. Between F’ and
V
CONCAVE LENS
F. At 2F’
G. At the Focal
point, F’
H. Between F’ and
V
Q21. Refer to Table 9. How does the image change in its size and
location, as the object comes nearer the convex lens? Concave
lens?
Q22. Refer to the size of object and the size of image from the drawn
ray diagrams for convex lens. Identify the location of object
for which the following optical instruments are used to. Match
column A with column B.
Column A Column B
photocopy “Xerox” Machine At Infinity
Camera Beyond 2F’
Telescope At 2F’
Projector Between 2F’ and F’
Magnifying Glass Between F’ and V
Q23. Why is it impossible for a concave lens to form a real image?

204
The Lens Equation
Ray diagram does not provide exact location and numerical information
about the image formed in lenses, as in the image formed in curved mirrors
through ray diagram. To determine the exact location and size of the image
formed in lenses, a lens equation is needed. The following derivation shows
the lens equation using the results from ray diagram.
From the first and third rays, similar triangles are seen in the diagram.
From the height of the object, h and the height of the image, h’ shown in
Figure 20 (a), you can arrive at the first equation,
Similarly, as shown in Figure 20(b), the second equation can be derived
as
Combining Equations 1 and 2, you will get
(b)(a)
Figure 20. Similar Triangles are Formed using the (a) first ray (P – F ray) and (b )third ray (V
ray).
Equation 1
Equation 2
Equation 3
Similar
Triangles
Similar
Triangles

205
Rearranging Equation 3, you will arrive at
and finally,
where: f = focal length or distance from the mirror and the focal point,F
p = distance of the object from the lens
q = distance of the image from the lens
The equation above, called mirror equation, applies to both convex
and concave lenses. However, in the case of the concave lens, the image will
always be located on the side where the object is also located. It is therefore
considered that the value of image distance, q is negative. The focal length, f
in a concave lens is negative while positive in a convex lens.
Sample Problem:
What is the image distance and image size if a 5.00-cm tall light bulb is
placed a distance of 45.5 cm from a convex lens having a focal length of 15.4
cm?
Given:
h = 5.00 cm
p = 45.5 cm
f = 15.4 c
Lens Equation

206
Find:
d = ?
q = ?
To determine the image distance, the lens equation must be used.
Since three of the four quantities in the magnification equation are
known, the height of the image, h can be calculated.
The negative values for image height indicate that the image is an inverted
image.
In the case of a concave lens, you found out that the image always
appears in front the lens. It is therefore considered that the value of image
distance, q is negative.

207
Sample Problem:
What is the image distance and image size if a 3.00-cm tall light bulb
is placed a distance of 30.5 cm from a diverging lens having a focal length of
-10.2 cm?
Given:
h = 3.00 cm
p = 30.5 cm
f = -10.2 cm
Find:
q = ?
h’ = ?
To determine the image distance, the lens equation will be used.
This confirms the image distance, q as negative. To determine the image
height, the magnification equation is needed. Since three of the four quantities
in the equation are known, the fourth quantity can be calculated. The solution
is shown below.

208
Try solving this…
1. Determine the image distance and image height for a 8.00-cm tall object
placed 46.5 cm from a convex lens having a focal length of 16.0 cm.
2. A 3.10-cm diameter coin is placed a distance of 25.0 cm from a concave
lens that has a focal length of -11.0 cm. Determine the image distance and
the diameter of the image.
So far, you have learned two of the properties of light which are the
reflection and refraction. You have gained concepts on the rules of reflection
and refraction to describe and explain how the images are formed by mirrors
and lenses. You also solved problems pertaining to the exact location and
magnification of images formed by mirrors and lenses. In this last activity on
Module 2, you will make use of these concepts you learned to improvise an
optical device. You will be asked to plan, brainstorm, design, and construct
one of the following optical devices.
The Sign Conventions for Lenses
• f is + if the lens is a double convex lens (converging lens)
• f is - if the lens is a double concave lens (diverging lens)
• q is + if the image is a real image and located behind the lens
• q is - if the image is a virtual image and located on the object’s
side of the lens
• h’ is + if the image is an upright image (and therefore, also
virtual)
• h’ is - if the image an inverted image (and therefore, also real)

209
Activity 9
Making Improvised Optical Device
Option 1: The Camera
Task:
• Construct a pin hole camera and explain the factors that affect the
image on the screen
Materials:
• illustration board/cardboard
• black cartolina, cutting mat
• pin/sewing needle, glue/sticky tape
• cutter, scissors, foot ruler, clear lamp
Procedure:
1. With your group mates and using the materials given, design and construct
an improvised camera based on the information gathered from different
resources.
2. A record sheet is provided to serve as your guide for accomplishing the
written report on your constructed camera. Refer to your copy of Attached
Assessment Tools: Problem Solving Sheet.
Option 2: The Periscope
Task:
• Construct a periscope and trace the incident and reflected rays.
Materials:
• 2 plane mirrors
• illustration board/cardboard
• cutting mat
• glue/sticky tape
• cutter, scissors, foot ruler, clear lamp

210
What to do:
1. With your group mates and using the materials given, design and construct
an improvised periscope based on the information gathered from different
resources.
2. A record sheet is provided to serve as your guide for accomplishing the
written report on your constructed periscope. Refer to your copy of Attached
Assessment Tools: Problem Solving Sheet.
Option 3: The Microscope
Task:
• Set up a simple microscope and investigate the factors affecting the
magnification capabilities of a microscope
Materials:
• set of lenses with different focal lengths
• specimen, light source, ruler or meter stick
• thin, clean sheet of paper to serve as the camera’s screen
What to do:
1. Using the materials given, construct or set up a simple microscope. Use
knowledge learned in the previous lesson and based on the information
gathered from different resources.
2. Discuss with your group mates and agree on one design.
3. Use the problem-solving record sheet as your guide for writing the report on
how you were able to construct your microscope.
Option 4: The Telescope
Task:
• Construct a simple telescope and investigate the factors affecting the
magnification capabilities of a telescope.
Materials:
• set of lenses with different focal lengths
specimen, light source, ruler or meter stick
thin, clean sheet of paper to serve as the camera’s screen

211
What to do:
1. Using the materials listed above, construct a telescope based on information
obtained from the previous lesson and other resources. After discussing
telescope with your teammates, design a simple telescope.
2. Use the problem-solving record sheet as your guide for writing the report on
how you were able to construct your telescope.
This activity is adapted from APEX Physics LP, Unit I, Chapter I, Lesson I Optical Instruments.

212
Problem Solving Sheet
Group No.: ______
Members: ___________________________________________________
Activity Title: ___________________________________________________
Problem: ___________________________________________________
Type of Problem:
construction discovery testing
Procedure:
What we did to solve the problem?
______________________________________________________________
______________________________________________________________
______________________________________________________________
Sketch/Diagram of the Device/Model Constructed
What concepts our group considered in the construction of the device?
______________________________________________________________
______________________________________________________________
______________________________________________________________
What our group found out?
______________________________________________________________
______________________________________________________________
______________________________________________________________
What our group recommends to improve the design/model built?
______________________________________________________________
______________________________________________________________
______________________________________________________________

213
• Reflection is the bouncing of light when it hits a surface.
• Two Laws of Reflection:
o The normal line, incident ray, and the reflected ray lie on the same
plane.
o The angle of incidence is equal to the angle of reflection.
• The reversal effect is the inversion of the image from left to right.
• Mirrors at an angle produce multiple images.
• Two Types of Reflection:
o Specular/ Regular Reflection – reflection of light on smooth
surfaces such as mirrors or a calm body of water.
o Diffuse/ Irregular Reflection – reflection of light on rough surfaces
such as clothing, paper, and the asphalt roadway.
• A curved mirror is a reflecting surface in which its surface is a section of
a sphere.
• Two Kinds of Spherical Mirrors:
o The Concave Mirror or Converging Mirror
o The Convex Mirror or Diverging Mirror
• Important Points in Ray Diagramming:
o Center of Curvature, C – the center of the sphere in which the
mirror is part. Its distance from the mirror is known as the radius.
o Vertex, V – the center of the mirror.
o Focal Point/ Focus, F – the point between the center of curvature
and vertex. Its distance from the mirror is known as the focal
length, f.
• The ‘Four Principal Rays’ in Curved Mirrors
o The P – F Ray is ray of light parallel to the principal axis, is
reflected passing through the principal focus, F (concave mirror),
and as if passing through the principal focus, F(convex mirror).
o The F – P Ray is a ray of light passing through F (concave mirror)
or directed towards F (convex mirror), is reflected parallel to the
principal axis.
o The C – C Ray is ray of light passing through the center of
curvature, C (concave mirror) or directed towards the center of
curvature, C (convex mirror) reflects back along its own path.

214
o V Ray is a ray of light directed to the vertex reflects at equal angle
from the principal axis
• Mirror Equation:
• A lens is a transparent material made of glass or plastic that refracts and
focuses (or that appears to focus) light rays at a point.
• Two Types of Lenses:
o Convex Lens or Converging Lens
o Concave Lens or Diverging Lens
• The ‘Three Most Useful Rays’ in Lenses:
o The P – F Ray is ray of light parallel to the principal axis is refracted
passing through the principal focus, F behind the lens (convex)
or as if passing through the principal focus, F in front of the lens
(concave).
o F – P Ray. A ray of light passing through F in front of the
lens(convex) or directed towards F behind the lens(concave) is
refracted parallel to the principal axis.
o V Ray. A ray of light passing through the exact center of the lens
(Vertex) continue to travel in the same direction.
• The Lens Equation
• The Magnification Equation

215
Directions. Choose the letter of the best answer.

1. As indicated by the hands of the clock without numbers, the real time is
9:30. What is the time indicated in its image if the clock is placed in front of
a plane mirror.
a. 2:30
b. 3:30
c. 9:30
d. 10:30
2. The entire two opposite walls in your room consist of plane mirrors, how
much larger will your room seem to appear?
a. 2x larger
b. 3x larger
c. 4x larger
d. infinite
3. If you stand in front of two adjacent large mirrors (at 90o
angle), how many
images will you see?
a. 1
b. 2
c. 3
d. 4
4. If you placed a number chart in front of a plane mirror, what numbers will
you read properly in the mirror?
a. 0, 1, 6, 8, and 9
b. 0, 1, and 6
c. 6 and 9
d. 0 and 8
5. An object is 6 cm in front of convex mirror with a focal length of 6 cm. What
is the location of the image formed?
a. Between F and V
b. Between C and F
c. In front of the mirror

216
6. A man 1.30-m tall stands 5.20 meters from a concave mirror. If the image
could be formed on a screen 15.0 cm from the mirror, what is the size of the
image?
a. 0.07 cm
b. 3.75 cm
c. 10.5 cm
d. 14.6 cm
7. What is the focal length of the mirror in no. 6?
a. 0.07 cm
b. 3.75 cm
c. 10.5 cm
d. 14.6 cm
8. An object is placed between a concave mirror and its focal point. What is
the type and orientation of the image formed?
a. virtual and inverted
b. virtual and erect
c. real and inverted
d. real and erect
9. A light ray, traveling parallel to a concave mirror’s axis, strikes the mirror’s
surface. What is the direction of the reflected ray?
a. It passes through the mirror’s focal point.
b. It travels again parallel to the mirror’s axis.
c. It travels at right angles to the mirror’s axis.
d. It passes through the mirror’s center of curvature.
10. An object is kept at a distance of 150 mm from a concave mirror with a
radius of curvature of 600 mm. Find the image distance.
a. -150 mm
b. 150 mm
c. -300 mm
d. 300 mm
11. Why is it easier to read a newspaper than a glossy magazine?
a. Because incident rays of light on a newspaper reflect in different
directions while incident rays of light on a glossy magazine reflect in
only one direction.
b. Because incident rays of light on a newspaper reflect in only one direction
while incident rays of light on a glossy magazine reflect in different
directions.
c. Because incident rays of light on a glossy magazine converge at the
focus.
d. Because incident rays of light on a newspaper converge at the focus.

217
12. What kind of mirror is used by department stores to give a wider area and
smaller image of the shoppers/buyers?
a. Plane mirror
b. Convex mirror
c. Concave mirror
13. If you look down on a pool of wavy water, you can’t see your face clearly.
Which one of the following gives the best explanation for this observation?
a. Light entering the water is dispersed.
b. Regular reflection of light happens on the surface of wavy water.
c. Irregular reflection of light happens on the surface of wavy water.
d. Light is reflected from the surface of water in the different direction.
14. Where should an object be placed in front of a concave mirror so that the
image will have the same size as the object?
a. At the focus
b. At the center of curvature
c. Between the focus and the vertex
d. Between the center of curvature and focus
15. Which of the following is/are true of a convex mirror?
I. It will never form a real image
II. An inverted image will be formed if the object distance is greater
than the focal length
III. An object can be magnified if it is placed at p = 3f
a. I only
b. II only
c. I and II
d. I, II, and III
16. A light ray traveling obliquely to a convex mirror’s axis, goes directly to the
mirror’s center of curvature before striking the mirror’s surface. What is the
direction of the reflected ray after hitting the mirror?
a. It travels parallel to the mirror’s axis
b. It passes through the mirror’s focal point
c. It travels at right angles to the mirror’s axis
d. It travels back through the mirror’s center of curvature.

218
17. What type of lens produces smaller and upright images?
a. Concave lens
b. Convex lens
c. Converging lens
18. An object is kept at a distance of 80.00 cm from a convex lens of focal
length 25.00 cm. Find the distance between its image and lens.
a. 19.05 cm
b. 25.25 cm
c. 36.36 cm
d. no image
19. A light ray, traveling parallel to the axis of a convex lens, strikes the lens.
What happens to this ray after traveling through the lens?
a. It travels crossing the axis at a point equal to twice the focal length.
b. It travels to the axis passing between the lens and its focal point.
c. It travels to the axis passing through its focal point.
d. It travels parallel to the principal axis.
20. Sun’s rays are observed to focus at a point behind the fishbowl near the
window. The fishbowl act as what type of lens?
a. Converging Lens
b. Diverging Lens
c. Focusing Lens

219
Glossary of Terms
Concave Lens a kind of lens that is thicker at the edges and thinner in
the center. It is called a diverging lens.
Concave Mirror a curved mirror in which the reflective surface bulges
away from the light source. It is called a converging
mirror.
Convex Lens a kind of lens that is thicker in the center than the edges.
It is called a converging lens.
Convex Mirror. a curved mirror in which the reflective surface bulges
towards the light source. It is called a diverging mirror.
Plane Mirror a polished or smooth surface (as of glass) that forms
images by reflection.
Reflection of Light the bouncing of light rays when it hits a surface.
Refraction of Light the bending of light rays when passing obliquely from
one medium into another.

220
Printed Materials:
Belen, J.G., A.I Yap, E.B Ogena, and A.I Yap. Addressing Misconceptions in
Mathematics and Science. Quezon City: NISMED UP Diliman and
DOST-SEI.
Littell, McDougal. Science, Integrated Course 1, Teacher’s Edition. Evanston,
Illinois: McDougal Littell, 2005.
Padua, Alicia, and Ricardo Crisostomo. Laboratory Manual and Workbook in
Physics. Vibal Publishing House, Inc., 2011.
Shipman, James, Jerry Wilson, and Charles Higgins, Jr. An Introduction
to Physical Science. Pasig City: Cengage Learning Asia Pte Ltd
(Philippine Branch), 2013.
Young, H. D., Freedman, R. A., Ford, A. L. (2012), Sears and Zemansky’s
University Physics with Modern Physics – 13th Ed., San Francisco:
Addison-Wesley Pearson Education, Inc.
Science and Technology Textbook for Fourth Year, Revised Edition, 2004,
SEMP.

221
Electronic Sources:
Henderson, Tom, . The Physics Classroom, “Specular vs. Diffuse Reflection.”
Accessed March 1, 2014. http://www.physicsclassroom.com/class/
refln/u13l1d.cfm.
The Mirror Equation. Accessed June 21, 2014. http://www.physicsclassroom.
com/class/refln/Lesson-3/The-Mirror-Equation
Ray Diagram – Concave Mirrors. Accessed June 22, 2014. http://www.
physicsclassroom.com/Class/refln/U13L3d.cfm#note
Ray Diagram – Convex Mirrors. Accessed June 22, 2014. http://www.
physicsclassroom.com/class/refln/Lesson-4/Ray-Diagrams-Convex-
Mirrors
Diverging Lenses – Ray Diagrams. Accessed June 23, 2014. http://www.
physicsclassroom.com/class/refrn/Lesson-5/Diverging-Lenses-Ray-
Diagrams
Physics Questions. Accessed October 15, 2014. http://www.sciencequiz.net/
lcphysics/light/mcq/reflection/reflection1a.htm
http://www.wallpaperup.com/225284/landscape_nature_trees_mountain_Mount_
Mayon_Philippines_Luzon_reflection_volcano_g.html
http://www.orcagrowfilm.com/Articles.asp?ID=148
http://www.wallpaperup.com/29790/sunset_mountains_reflection.html
http://www.education.com/science-fair/article/how-many-images-make-mirrors/

222
Appendix A
A Paper Protractor

GRADE 10 SCI MODULE UNIT 2

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GRADE 10 SCI MODULE UNIT 2